You can brush it while it's short, but once it gets around 2 inches you should comb it in order to give it direction. Invest in a good conditioner to prevent flakes and to make it easier to tame. Honest Amish is pretty good. Try to find a good barber to remove loose ends (#1 reason why ppl cut their beards is because they fuk it up by trimming themselves).
Would also invest in a wax or a good beeswax to stop little hairs from sticking out. Your beard will only stay down once the hairs are long enough to be pulled down by gravity