an

I want to buy some sais and start practicing with them. I want to get a pair and also a video or book or something to start off some training before I go out and spend a lot of money on lessons. I have no experience with them, however, and I do not know what size to get. I have seen anywhere from 13" - 22". How do I secode what size is the best for me? Any help would be appreciated. Thank you. -Tony