I’ve been putting off talking about brushes because I treat mine so badly. Hog Bristle is my brush of choice, and I often scrub with them and use them until they’ve been worn down into a whole new shape!
Brushes come in many sizes and types. Both synthetic and natural bristle brushes are great for acrylic, and each has its advantages. Natural bristle brushes are best for soft edges and drybrush, and synthetics hold a lot of paint and generally make harder edges. I personally like brights, a rather square brush with shorter bristles because they’re a little stiffer than longer bristled flats, great for scrubbing, but as Emil Gruppe would say, “why pay for less, since you’ll eventually wear it down anyway!”
As you become familiar with different brushes you will probably only use only a few favorites most of the time. But for some people, it’s almost like shoes and you can never have enough. If you do collect a few of each kind and you will occasionally find uses for most of them. Before ordering brushes, go to an art supply store and hold and feel a number of brushes to see what feels best in your hand. If you are just staring out, you can get by with a few flats and filberts, and a rigger, or thin, pointed brush for signing paintings. A couple of rounds are good, too, since they are versatile and very responsive to ary and hand movements in the early stages of a painting.
Start your block-out with the largest brush you can and work over the whole canvas. You can decrease in brush size as the painting progresses. It’s always a mistake to get tied up nitty-gritty small brush details before you have developed the underlying character of the painting.