My first mirror was a 12.5" f/6. It was a bit of a steep learning curve but I did it with out any help other than a good book. One book that I feel is a must is "How to Make a Telescope" by Jean Texereau. You could go with a f/6 or f/7 without much trouble. This is a fun hobby so you should enjoy it very much. Its not as hard to make a good mirror as one might think. When you are ready to have it aluminized just let us know and we can tell you of some good places to have it done. So, "get er done".