Spots are caused by the white cells moving out of the blood and into the skin where they collect to make that sore angry looking spot. Sometimes this is because of an infection like a bacteria so antibiotics will work (sometimes the doctor will prescribe these drugs for bad acne). Sometimes its to do with facial hair not coming out of the skin properly or even growing back into the same hole and this causes the inflammation. Other times its to do with hormones when you go through puberty so some women benefit from hormones like the contraceptive pill. Keeping the skin clean and removing dead and flaky skin helps too.
Keep your face clean, exfoliate and try not to pick the spots — this is probably the hard part!
Some people may go through hormonal/puberty changes which makes spots more likely, as can certain types of contraceptive pill. If the spots look red and inflamed, it is always worth seeing your doctor to check that there isn’t an infection.