@dogboy You don't need to be able to draw or sketch. There are loads of patterns around that you can copy and others that you can purchase. The majority of the usual tooling process is basically learning the mechanics of the sequence, which side of the line to bevel, etc. If you are talking about figure carving of animals, scenes, portraits, etc. then that becomes a different story. You need to have some artistic talents and skills.
There are a number of books available showing how to do tooling and carving. Also some really good videos on YouTube. Jim Linnell has a series of lessons at https://www.google.com/search?q=youtube+jim+linnel&ie=utf-8&oe=utf-8
Tom