How do you place objects like fence, trees etc on a terrain accurately? It seems so hard to do just pushing them around in the four views. Also, how are people making sidewalks, paths and roads so accurately? Thank you.

Well, I generally drag things roughly into place using the top view then use the other ones to fine tune it.  Once you get used to doing it that way it's pretty quick.

For making roads and paths etc. your best bet would be to use a mixed material and drive the mix with a greyscale image - have a look at the tutorials over at Geekatplay.com.  I think there is one or two in there about it.  Artur Rosa (Rutra) did a brilliant one on how to do that sort of thing.  There should be a thread somewhere in here where he explains it

Thank you!!!!

I have played around with towers on terrain recently. One effective way to make sure an object is well placed is to work in two stages:

• place it roughly in the 4 view, using the displayed terrain as a reference (might not be accurate)
• create a specific camera. Center the object in it. Rotate around the object and make test renders of the junction.