small or medium drybrush, which is best for a beginner, i have the starter brush and fine detail brush
I recommend something really large, like a wash brush to do basecoating. especially with LM you can do very very much of the painting with a large brush, saving lots of time. for smaller parts i use a "large" brush. it has a good tip, but it also holds a lot of paint making it both faster and easier to use. Also, get a special (or two) brush for drybrushing. not because it requires a special brush, but because it destroys the tip of teh brush. i use very cheap brushes for this. i got 15 for about 7 euro at "rusta" (some swedish kind of wallmart). this sabes your other brushes for better things. one very large and one smaller drybrush should be enough. lastly, i use a 000 brush for eyes and pretty much nothing else. This is NOT a very important brush and your fine detail brush will serve you well untill you no longer concider yourself a ”noob” (or rather the bush will wear out before that Many people make the mistake of focusing too much on small brushes and small details. a larger brush gives an even coverage and saves time. with a wash brush and a large drybrush you can make fantastic looking models by using drybushing and washing. You dont need the tiny details like eyes untill you are an expert with drybrushing and washing. Always use as large a brush as you can, and the mores killed you get the larger a brush you can use with precision. GL
also keep in mind there are many brush shapes besides just pointy, I use a lot of flat square and chiseled ends myself, I find the flat wide brushes work best for dry brushing, so get a variety back of some cheep natural bristle brushes, just stay from the coarser bristle brushes, those are terrible for miniature painting.
I use a #2 shader for my drybrush. It's made by Loew-Cornell. It's fairly small I've used the white nylon for them before, but i find it's a bit TOO soft so I use the blue handled ones (i can't remember the material it's made out of). Another brush that works fine (after you've worn it out) is a #0 spotter, it's a round flat tip brush and works well, mine is fine sable. Has a good firmnes, but not so firm as it wipes the paint right back off again
Honestly if you are just starting go to a craft store and buy a variety of the medium priced ones, don't buy the crap ones, but don't buy the really nice ones until you learn to care for the brushes. It also helps you discover which size brushes you like.