Frustration is easier to avoid when you know why issues happen to your model.
Guys, I learned these tips the hard way and forgot I learned them until I started to help Universities implement Sketchup. After looking at the first 20 models, I knew I had to make a tutorial explaining how to avoid model bloat and lag.
I did the tutorial straight off the top of my head with 5 minutes of prep so if I missed anything, feel free to point it out.