Tip #1
Know your final output. Before you begin a project you should have a good idea of what your final product will be. This will keep you on track and prevent many hours wasted on frivolous elements and details that in the end are never used or seen.

Tip #2
Only build what you see. When you draw an elevation do you draw the interior behind the wall and then make a hidden line plot? No you only draw what you see. Same thing in 3d. Only model what you see. There is no need to put the doorknob on the back of the door, if you never see it. This will save you lots of polygons of render time, as well as hours of construction time. At the same time, don't go overboard on details if you're never close enough to see them.

Tip #3
Don't waste time modeling what you can do in a material. Your renderer will be very appreciative. Sure it is nice to put rivet heads on the structural plates in your steel work, but if you are really getting close enough to see that, you could probably achieve the same result with a bump map. Spend some time with your 3d package and see what you can accomplish with materials.

Sometimes you may even want to consider making separate scenes per view. This way you can set up your lights and materials to the specific views while keeping your file sizes and poly counts low.

Lastly, if you're serious about 3D, take the time to study photography, film, and video techniques. The best 3d software can only closely replicate real life situations. If you don't understand these, you're just wasting your time.

Part II - rendering for video

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