First, exfoliate exfoliate exfoliate clean skin is good skin
Acne medication usually works, but I've found that antibacterial ointment like Neosporin works really well, especially on large clusters of acne
Make sure your face is clean, then (if you don't have sensitive skin) apply an acne medication. After this apply the ointment in thick globs all over the infected area. I've found it works best if you leave it on overnight, though it'll also work if you just leave it on during sessions throughout the day. Just remember to remove it before going out, or you'll look a little silly.
I used to have terrible face and back acne. I tried EVERYTHING. Neosporin was the only thing that made a notable difference overnight