I agree with Anton , I look at lots of gallery renders and do not like them because the models are stareing off somewere else . The eyes draw you in and make you feel more conected to the render. Another important thing is focal point or the spot in the render that first draws your eyes attention. You can build a render from that point outwards or crop a render to get a better spot. I call it the sweet spot. Try to start your renders with just one model and move it around getting it just right , then work your way out and add stuff to it . Move it around till it feels / looks right. Stop thinking to much when you do it, get a general idea of what you want and have fun like Stormrage said .