I browsed through the brushes once, and uninstalled. I repeated a couple times over time because I really want to find an alternative to photoshop, and here I am again. I can't find the most basic brush.

Here's how it goes:
pick a brush
looks good
increase size
it turns into a blurry piece of ****

Am I missing something, or what am I supposed to do?

Go to the brush setting and increase the fade setting. That will make a sharper fall-off at the edges.