You can divide painting into two stages. A person willing to work hard and not give up can learn how to do the first stage. The second stage is more of a skilled operation.
The first stage is to get the surface perfectly smooth, covered completely with one product, and all totally one color. Metal work, fillers, sealers, surfacers, primers, guide coats are some of the products that may be needed. All along the way there are clever practical ways to undo any mistakes you make. You can keep working until the surface is perfect.
The second phase is to apply the color (and the clear coat if that is the system you are using). To simplify, you are trying to achieve even coverage while avoiding the opposite problems of orange peel and runs. Too little paint on the surface = no flow-out= orange peel. Too much paint = runs. Fixing orange peel and runs is labor intensive and changes what should be a quick job into an extremely long one. In the case of metallics, true candies, pearls, and color-changing paint it is much harder to spray the stuff and difficult to impossible to fix mistakes.
A reasonable way to get a good paint job is to first find a local painter who will talk to you, ask him what products he wants you to use for phase one, then have them spray the color.
If you want to do it all yourself, use one company's products all the way through the process. The company should have someone you can call for advice about your problems. If you are mixing products from different companies, you can't blame the tech adviser for not being able to help you. The chemists are constantly tinkering with ingredients to keep their products working well with their other products (not their competitor's products).
Get something like a junked hood, wash it good and try spraying it with a spray can. You will probably find out quickly if you enjoy it and it looks good, or else you will realize that it would take too just too much expensive annoying practice to get good at it.