Have had a little bit. What are you making? If you are holding moving pieces, the biggest thing is to get the shank to fill the hole(s) before fully forming the head. So the shank generally has to swell. If the rivet is too long, the shank often bends over and the to be formed head will look like sh@#t. A good backing bar/ block is important, nice if it has a dimple that is head shaped, the bigger, the better, if it will fit in the area/space. Yes, a hammer can and has been used by many!
If you are making a liquid holding tank, put sealant/gasket between the 2 pieces, then rivet together (how do I know, $%&@). A very light champher on the edges of the hole helps.
Much you may already know.