Atlas publishes a series of short how-to booklets. There is one that is just on track plans -- I have it at home and could get its title if you'd like. Otherwise, you could just google Atlas and probably find it on their website. Many hobby shops also carry these Atlas books.
If I was starting over, I'd strictly follow a track plan. I built my current 4x6 layout totally by trial and error, and guesswork, which is probably why I've had so many problems in the past. It's working well now, though!
Rob