Everything works better when you're KIS'ing, as a developper I can tell you that keeping it simple doesn't mean to write simple code. You can build something and work hard, that's good, the simple part should be understanding it and modifying it when the next developper steps in your things.

Same thing for database and table structures... you should knock your head on the wall making them as pure as possible, so it can be understood more quickly by the next kid who has to work in them.