Second Life Build Policies
Prims for Architecture, Mesh for Furniture.
The most efficient use of resources is generally prims for architecture and Mesh for Furniture. From a distance, a prim wall or flor covered with a properly applied and matched texture looks as good as a mesh wall or floor. Prims are easier to torture into required shapes than mesh. Mesh does not solve role-play problems.
Play Prim Golf.
Try to build your thing in as few prims as you can. Practice.
Full Bright, Shiny, Glow, Light Source
Use lighting effects sparingly.
Shiny and Glow reduce the readility of signs: Do not use these effects for signs. Fulll Bright makes signs visible even at midnight with no additional lighting. If you want a sign to look like it's lit up and you want people to actualy read it, set it tp Full Bright. Please look at the tutorial Timberwoof's Balls.
Minimize Light Sources. 
OpenGL can only handle 8 light sources in a single scene. WIth the Sun and Moon, that's six in the scene. Light sources cause veiwer-side lag. Don't be cruel to people who didn't spend as much money as you did on a fast and big GPU.