A mallet.
The best way to begin your leatherworking career is to make a leather belt. This is because leather belts are the easiest to make and you will most likely not fail. From then, get a peice piece of leather of high-ish QL and improve the belt until you need another tool. Keep improving it and you will gain skill. Once you have a higher chance on other items, make lots of gloves and improve them all to 15QL. Keep doing this with higher dificulty items and once your skill reaches 10-15. Try and stud some of them (it takes 0.2 kg of rivets to stud ALL leather items apart from leather pants which take 0.8 and leather jackets which take 0.64)
==Lock Smithing==