Don't forget to have fun. If this is a learning project or something just for you, don't worry too much about correctness. Just have a good time and pay attention. If you need to refactor later, that can also be fun and a learning experience. Trying to get something perfect up front can be a bit paralyzing and counterproductive. Treating first stabs as prototypes can dig out the real issues you'll face for a robust final version.

There is a great quote in the intro to a chapter of one of the Perl books (which I don't have in front of me). Something along the lines of: It is faster to build a four inch telescope and then a six inch telescope, than it is to build a six inch telescope.