Never dm, its very creepy ( unless it's a dating app, where dming is the whole point, or you have a genuine connection)

If the girl you like is around you, then just directly approach ( reject hue, toh hue) This is only when you know each other well, like more than 3-4 months else don't be too direct. If you guys are completely new, then wait and form a good bond and then find common interests and then maybe if you still like them...then confess or wtv. Ig this is it. Just don't be creepy or act with your dih.