Probably your best bet will be to get to a model show, or shop, where you can handle brushes, and choose one that feels comfortable. Several club members use Badger brushes, but I have large hands, so they always feel a little flimsy (though they aren't,) so I bought a Paasche VL, which is big, fairly heavy, and feels "right." That was 30 years ago, and it's still going strong.
There are two basic types, single action and double action. With the first, you set the spray width, then spray the paint; with the second, the spray width is adjustable as you spray. The double action is usually more expensive, but, while you learn, it's possible to use the double action as a single action, but not vice versa. It will be tempting to go for a cheap, cheerful mass-produced brush, but that direction is fraught with danger, since spares and repairs might be impossible, or downright expensive.
At some time, it's fairly certain that you'll find a need for a compressor, rather than rely on cans of air, which are dreadfully expensive, gradually lose pressure, and have a nasty habit of dying just when you have no spare, and it's Sunday, so the shops are shut. A compressor will need to supply at least .5 cu. ft. of air per minute, and, again, you get what you pay for, so looking at several is a must.
Edgar