One thing new users want to watch out for is what I call "this for that" syndrome.

Read the editorials carefully before you make any purchases and make sure you uderstand exactly what you are getting and what it is meant for.

For every outfit, model, or prop that comes out, there will be a slew of texture options released in short order for it. So, if you see hair you really like for example, make sure it is not a texture pack for an orignal hair figure you have to buy first.

I know that's not Poser operations specific, but it's gonna come up sooner or later.

As far as using Poser for rendering, learn the material room and the how the lighting works and it will increase the quality of your renders by a huge amount.

I could go on all day, but one other thing to make note of is that since you are coming from Blender and no doubt have it in your mind to make your own Poser Props, Poser requires certain "irregularities" to be optimized correctly before it will play well with the object. I have made this mistake a few times and had a really nice model in Blender only to have it explode or do something unexpected in Poser. Watch out for the triangles ;-)