Well I suggest that if you do make a mod on your own, make it a small one. For example, at the moment I am working on my first real mod, called "Creatures of the Night". It is a mod about Vampires, and the only real changes in the game are Traits and Ancillaries made for vampire characters. Don't go for something too big on your first swallow.

Another idea is to join a mod team (I'm part of the Inca: Total War mod team as well). Trying to make your own mod team when you have little modding experience is generally a bad idea. If you join a team, you can better understand how other aspects of modding work, and chances are the people in your team will be happy to help you improve your skills.

Good luck!