it's not gonna be easy for them to tell ya how to fix this. my suggestion is to go to acadia's thread on lighting that she recently started here. I hope there's also a good thread on render settings (depending on poser version), but I haven't seen one lately.

Depending on what you're trying to achieve, a more dynamic camera angle might help - a view more from one side. Also, to get the feeling as if you're in a cemetary, you could move into the scene a little and play with the cameras perspective so that you get some grave stones larger in the foreground of your scene. Some kind of grass texture on the ground and even some grass objects (some good freebie ones in freestuff from RDNA - if you have P7 I think they're in the RDNA props content library).
Shadows - where there's light there's always some kind of shadows. If your scene is a moonlit night then there'd be some kind of shadows cast from the moon. Or maybe from that light on the cemetary wall if it was lit. Shadows add a huge sense of depth to any scene - there's a whole lot of experimentation you could do there.

Hope this helps some. Keep going - love the trees BTW.

The concept itself is nice and you are on the right track so far as placement and balance is concerned.  But it does however look a tad flat without any depth because there doesn't seem to be any shadows.

If you are using IBL lighting, it doesn't cast shadows.  You will have to add an infinite light or two to the scene for shadows to be cast.

Lighting is a really hard concept to try and learn in Poser. It's really advanced.  If you are using Poser 5, a good lighting scene can take up to 20 or more lights to place around the scene.  With Poser 6 and Poser 7, you don't need as many lights, but the IBL and AO gives it a whole new set challenges.

My advice to you as a new user to Poser  is to go to RDNA and download some or all of their free light sets in their free area.  They have lots of great lights and they all work very well in Poser 5 and Poser 6. I use them quite a bit myself.

http://www.runtimedna.com/mod/forum/

Once you have some shadows in that picture to provide some depth  that will be a really great image :)

EDIT:  A nice creepy background picture behind would be a nice addition too.

You can find lots of free backgrounds in this thread:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2678784

i think your first step should be where nancy suggested...camera angle, and then lighting.

go watch an old alfred hitchcock movie for examples of great camera angles and lighting techniques. learn from a master, eh?

Also you might want to make some of your headstones tilt a bit. It looks like an old cemetary but it is too perfect. I load my props and then get a picture of what I want in my head and try to move stuff around to match that picture. Lighting is important for shadows and depth. Don't get discouraged it takes time to get it just right. Go out and find some cemetary pics you like and see if you can get that look then work on your own. 
Marque

marque makes a good point there. going to some of the old churchyards in england, one sees how the stones have shifted over the years, eroded, gotten covered with lichen in relatively coal-free areas, been broken or even fallen over, etc.

IMO things that can be improved :

1. The pic has no horizon or objects in the distance. This makes it very hard to judge what the scale of the pic is. ie are those real graves or models of them on a table top somewhere.

2. The placement of everything is too random. Not only does this make for bad composition, but IRL cemeteries dont just plop down the graves anywhere. They have an ordered structure that you should look for in refs.

3. Shadows in scene. A situation like this can be helped a lot by having some nice shadows. Makes the cubical forms pop out more and goes with the spooky theme.

4. The light from the right/behind is a warm orange. Given how cloudy the scene is (and actually looks like night) where is this warm light coming from ? You almost expect a lit torch or a fire nearby casting that light. But no such light source is visible anywhere.

5. The trees are very distracting. Unless the focus of the image is the trees themselves, you should change their look and/or add DOF blur to recede them into the background.

You need to add something behind the fence; A landscape, moon or something (maybe an old village on top of a hill). Allso a little fog would look nice. The ground looks a little bland. Add some more detail there (dead grass, bones, candles..etc). But just add a full moon there first, in the background. I know it's very cliche, but it will work non the less. You need to make it look more dramatic. Fog and full moon allways work. ;)

 Tilt the camera slightly. Colour some of the lights blue. Things like that.

I thought about shadows myself. I turned them all off because I was getting shadows on the background. I'm guessing I need to do the background differently. I couldn't get a background to show up so I put in skydome and changed the texture. How do you put in a background so you don't get a shadow on it? 

Fog would be cool! How would I add that? In postwork?

Thanks for all the suggestions

Some other things to consider are:

1. Nothing is at perfect angles, ever. Rotating things by a few degrees along the X,Y, and/or Z often makes it more realistic

2. You need ground. Everything is too level. A terrain type ground would do wonders for you.

3. Everything else everyone else said already.

I have a free fog plane prop on my Homepage, it's a very simple (but also very light on the processor) type of fog. Of course you can also make fog with volumetric lightning, but it takes ages to render and it's hard to get right.

And it definitely lacks shadows. I also agree with the light being of a wrong colour. At night they should be dark, blueish, not warm orange.

Change to a wider angle lens.  Your flat camera makes the markers all seem to close together...

Quote - How do you put in a background so you don't get a shadow on it? 

Fog would be cool! How would I add that? In postwork?

Thanks for all the suggestions

You can always just add your background in your graphic program.

What I do with all of my renders if they are going to have a background image:

1.  Set up your scene with everything you want including the background. Add the background using the technique in step #2

2.  Add a single sided square to your scene.  This is found in the props folder of the Poser runtime folder.  Go to the material room and right click in the working area. PIck "New Node", "2D_Image Node" and then "Image_Map".  Browse to the background you want to use. Plug that node into the 1st and 3rd channels.    You have just made your background into a prop so that it will interact with your scene including picking up the light in your scene and it allows you to turn your background and move it around unlike when you "import" it.

Now go back to the Pose Room and use the X Y Z scale files to make the square the same dimensions as your background image IE: 1024 x 768  or whatever it might be.  Then use the Z Trans and Scale to push back the square so that it's behind the scene and then Scale it up to whatever you need so that it works as a background for you. 

3.  Use the parameter dial options to make your single sided square invisible.  You want to render the scene without a background.

4.  Set your render settings so that  you are  rendering your scene over black.  I found that if I used any other colour that  there was a 1 pixel border of that background colour around all of the edges, and very noticable if I later wanted to put that image on a dark background.

1. Save your render as a .png file.

2. Now go back into the Pose Room. Make your single sided square visible again. Hide everything else in the scene.

3. Render the prop / background.  Save as a .png when done.

8.  Open both renders in your graphic program.  Paste the background into your scene image and drag it to the bottom.  The background now has the same lighting as the rest of the scene, but it doesn't have any shadows.

As far as Fog goes, you can read this thread to find out some techiques and ways to add it:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2502535

Here are some tutorials that show you how to add fog in post work:

http://www.daz3d.com/i.x/tutorial/tutorial/-/?id=711

http://www.daz3d.com/i.x/tutorial/tutorial/-/?id=1036

http://www.daz3d.com/i.x/tutorial/tutorial/-/?id=1681

http://www.daz3d.com/i.x/tutorial/tutorial/-/?id=1744

http://www.daz3d.com/i.x/tutorial/tutorial/-/?id=1750

Most of things I thought of was already mentioned, so time for something else ;) Even very well kept cemetaries do not have completely flat ground - you'd need some bumpy ground (TrekkieGrrrl have morphing square and morphing sheet props freebies, any of them slightly morphed makes great ground prop without being too heavy on the rendering speed). Maybe add a patch of grass here and there, that happens on cemetaries too. Good luck, the pic still is a nice start :)

I only skimmed the responses, so I don't know if this was mentioned (I know many other good things were):

Depth of field is important, and you should put it at the top of your list.

A camera generally shows us sharp focus on objects in a relatively narrow slice of space (depending primarily on apperture and lens factors).

This generally means far background objects and close foreground objects should be out-of-focus to some degree.   Our eyes and our subconscious immediately pick up on a scene where there is supposed to be depth, yet everything is in sharp focus as "fake".  This kills the illusion of realism.

You can do this inside the render (warning -- increases render time a great deal) or you can chaet it after the render by adding selective blurring to objects yourself.

Attached Link: http://ockhamsbungalow.com/MiscProps/Graveyard.zip

That looks much better.  My easy suggestion for terrain: magnets.  Select your ground prop, and add a few magnets, taking care to use various sizes for the influence zones.  Then you can pull and sculpt the ground to your liking and create a morph target when you're done.  It's nice to see all of the suggestions coming together in a much improved image!

coming along nicely, much better, the camera angle is still alittle headon, but the rest is much better

My only other suggestion would be to use a background Image that already has some shadowy trees, and perhaps a brighter moon in it, to give a sense of depth.

That next image is much better.

Many people forget that dynamic composition brings life to an image, Forget that its a building, some walls and a few happy little grave stones.
Try reading some books about drawing and composition, even if you can't draw, the basic principles of picture composition apply to 3D rendering as well. Try squinting at the picure so that your eyes go out of focus, does it look like a grid? Boring. Note how when you threw in a little perspective, the diagonal directions added life to your rendering.

Remember, think Diagonals. Circles, motion, diagonals lead your eye around the canvas and invite the viewer to look longer.

And add corpses. Every good graveyard scene should have a few corpses tastefully strewn about.

Looks better :)

If you still don't have anything to act as a terrain, and don't feel too good at using magnets, try this - Grassy, bumpy, terrain prop (if it's too bright/too green, change its Diffuse Color to a shade of grey, the texture will appear darker).
http://www.planit3d.com/source/poser/p_props.html

Or if you want to have a bit of control on the how bumpy the ground is, try either Trekkie's Super Morph Sheet (Morphing Props, page 2) or her Super Morph Square (Morphing Props, page 3). Add your own texture, use some morphs like Crumple or Wave at low values and you're ready to go :)
http://trekkiegrrrl.dk

just a note:
if you want a plain ol background rendered with your scene, and don't want it to take shadows, just hook the texture into ambient color instead of diffuse color.

there are also lots of terrain props in freestuff, and i believe stonemason (master of displacement) even has a freebie graveyard...

oops, my mistake, it's just a single grave:
http://home.xtra.co.nz/hosts/polycount3d/Freestuff.htm