I've been trying to avoid most posts don't involve me negative comments. If you don't see me throw something in you should know 100% why. I don't want to go off on somebody for asking a stupid question that has been answered 10 times already or asking a question in response to a correct answer, too many people are set in their ways and ask what might be wrong despite already "knowing" what the problem is.
Sorry if thats a rant but it makes sense.
On topic, if you're looking for go-kart plans, avoid Northern Tool's book, if you ride on the road typically stick with something without suspension and one wheel drive, if you ride off-road and have a decent budget go with something involving suspension but not extensive intricacy. If you're loaded to the gills with money buy a sand rail and paint it a different color and say you built it.