Here's how you paint something (for example, this random shelf that you use for towels in your bathroom):
2- Prime all the edges.
"But my paint has primer in it!"
The whimsical painting of furniture that you are getting yourself into probably involves painting surfaces that have no business being painted. You're way better off just getting in the habit of priming.
3- Prime the rest of it. With a roller. Like the grown ass lady you are. This is not third grade art class. You need a roller even for a job that seems small.
4- Wrap up your brush & roller very tightly in plastic bags (grocery is fine). You want the paint to stick to the bag & for it to get as little air as possible so that they don't dry out during the next step.
5- Watch an episode of Orange Is the New Black (or two episodes of Arrested Development, depending on where you are in life).
6- Reprime everything in the same order (edges then everything else). You want the original color to be kind of a mystery. Wash your brush and your roller really, really well or you will be sad later.
7- Go hang out at your friend's pool. Feel real fancy.
8- Draft a mediocre fantasy football team because there are some things you can only care so much about.
9- Figure out where you put that Oops Paint you bought on a whim a few months ago.
10- The primer should be dry enough now, go ahead and paint, in the same order you primed.
11- Stop being such a weenie, you probably won't run out of paint.
12- Once it is all painted and you haven't missed anything and you've checked four times, give the cat a quick talking to about not getting near the paint. Wash all the things.
13- Wait a day. Find all the spots you missed. Paint one more time.