I like compact coasters a lot too, although I haven't finished many.
Look at all the old Schwarzkopf coasters, like Jet Star I. (it's extremely compact). He made the tracks in many levels and blocks. They had two sides with space in the middle. Lift(s) were on one side and the final brakes on other. The sides change to make it more exciting.
My tip is to follow the rule of almost every other turn to right and every other to left and after building the first turn, think how it could go on another as compactly as possible. Do this a couple of times and after the track goes through the area as many times as you'd plan, build even one more lap. Even if you wouldn't have space, try raising the track pieces in the 3d view a little higher.