Creating a proper lift (3 sections with a long straight piece in the center). My lifts used to be all one piece and I'd mess with the verticees to control the "appearance" of the lift.
making fun tracks??? I don't know, it didn't take me long to figure out how to build lifts, I think probably the dumbest thing would be the hights, before I found out about the hight thing, I built things out of proportion (check out my medusa)
Mine was also trying to figure out how to make the track go up verticaly. The guides you get with the game dont tell you anything about it, plus it was back in 2001, so i was 14.