The key here is to start from the beginning and do every practice they give you. They will tell you explicitly what keys to press, what buttons to use. There's no need for a manual at all. Once you learn a skill, use it a LOT. The game gets very complex by the end and requires that you're good at shooting, good at riding horses, good at pretty much every skill there is. The only way you will become good at these things is to practice them frequently.

Your main stats are:
gunhand
quickdraw
melee
horse
health

All start at zero. You max them all out at the end of the game if you do everything. You can also see game stats as you progress, to know what is still remaining to be done.

You begin with $40 cash and 18 item / upgrade locations. Each spot only holds one type of stat, so for example if you keep upgrading your reload ability, that only occupies one spot regardless of what level it is.

Gun Walkthrough