Once your skill reaches 10-15 (EDIT - I would have said 20-25 but this depends on if you like making rivets :Shweet), 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 kg and leather jackets which take 0.4 kg. If you fail to stud an item you will lose the item and the rivet. Rivet ql and leatherworking skill will determine the % chance to succeed when riveting leather armour, not the ql of the leather item to be studded. Tip; combine rivets before improving them.
As your skill goes up you will need better quality tools as the quality of your tools will determine the failure rate when improving. You Your leatherworking skill level limits the max improving quality. You can improve with raw leather that has lower quality than the item you are improving you will however suffer from larger fail to improve rates. The only item used that has its own skill is a mallet; the miscellaneous skill “hammer” will effect your ability to successfully improve with the mallet.
As with other skills you will gain the most skill by improving the item rather than creating them, and when the item quality is closer to your skill you will also gain the most skill. Working on drake armour gives a greater skill gain than plain or studded leather armour.