Human Leather claims to use the skin of willing donors who signed off on turning their bodies into belts, wallets and shoes before death.
Ouch. Seems like after death would be a better option...
Re types of leather: Some's thicker, some's thinner, and of course, there's additional treatment depending on whether you want leather with or without the fur attached, but from a processing perspective, anything you can do with cow or deer hide, you could theoretically do with human hide.
I agree with Cobalt Jade that human skin is thicker than that of furred animals, but if there were a ready supply and no ick factor, I think there could, theoretically, be human haberdasheries. If I had to guess, I'd say the commercial leather most similar to humans would be pig leather, which is also quite thick, so you could look at pig leather products to get an idea of what characteristics you could expect.
Any leather, though, can be either left tough or made soft and pliable. (Look at cow leather, which is used to make everything from soft suede jackets to saddles and rawhide bones). If it's simply left out to dry, the resulting product will be tough and stiff. The more leather is worked (stretching and pulling in all different directions) as it dries, the softer the end product. There are a variety of substances that may be applied to the leather before and during the working process to help break down the connective tissues and aid in making the leather as soft as possible. Apart from modern chemicals, traditional substances include urine, eggs, or, most readily available, the brain of the animal being skinned. (Insert mandatory classic pun that each animal has just enough brains to preserve its own hide).
The details will depend on what you need for your story, but whatever use you have in mind for human leather in your story, it should be doable.
ETA: I don't know the details of your story, but the other element to consider is that human tissue is a biohazard, where animal tissue isn't (unless the animal is known to have died of a zoonotic disease such as rabies). Look at the difference in safety procedures between a butcher shop and a morgue to see the contrast. Unless your human-skinning character is an alien or something, they'd be at risk of contracting all kinds of stuff.
