Hobby Lobby sells those french clips in different sizes. Sally's Beauty sells the alligator clips. So does Michelle here at HipGirl.
As for ribbon...you can find ribbon (I prefer grosgrain(texture)) at Hobby Lobby, Michaels, Wal Mart, JoAnns, and many different sites on here including this one. As for ribbon and what sizes...take a look at what everyone is making and you can get an idea. Everyone uses all different sizes and prints. I picked up a lot just looking and reading everyone's posts showing off their creations.
There is also a number of places that give free instructions on how to make bows as well. Here is one of them Free Hair Bow Instructions: hairbow free directions, hair bow business work at home
You will need a hot glue gun, hot glue sticks, wire or thread to secure your bows.
Hope this sets you off in the right direction.