All these answers are good... take a class, start small and keep it simple.
Of course I did none of these things. I bought a book (for idiots), after working through the blocks in the book found others on the internet and eventually ended up making a king sized quilt. Even doing my own quilting.
My advice, "just do it". If a block doesn't work out, it can just be a pillow to go with your quilt. I waited for years before I started, using all kinds of excuses such as not enough time or space. Now I see all the fun I have missed.
So good luck and hope you that enjoy it as much as I do.