Don't overthink painting figures too much- it's the type of hobby where you start off with a few paints and some cheap brushes, then go through a journeyman phase of tons of specialized paints, brushes, tools, etc, then run into a real master who uses a few paints and some cheap brushes.
Basically, just start by trying to get color onto the right part of the figure, then watch some videos on how to use shades and highlights to add depth and texture. Play with the different techniques, buy some specific brushes or tools to make those techniques easier or more consistent, ditch the techniques that don't seem to work for you.
Look for 'Sonic Sledgehammer' on youtube for a good way to start, at least for Warhammer sized figures. His focus is for people who need to paint a bunch of figures in something of a hurry, but that means you can get a decent looking individual figure in an evening, which is encouraging. He'll usually call out optional extra steps to add more depth or detail, which gives you a good idea of how more advanced techniques work when you're ready.