Most Helpful Guy
He has to do it himself, if you try to force compliments like saying "hey do I look good in this" they are fake and don't really mean anything.
Most Helpful Girl
You could start complimenting him often, and maybe that would raise his self-esteem to a point where he can openly compliment you if it's something that's difficult for him to do. Some guys don't compliment girls very often because they're used to the girl being dismissive of their compliments, and may even take it as a form of rejection.
In the end, some guys just aren't very expressive with their words, but they might be silently complimenting you in other ways like hugging you close to them, squeezing your hand gently when the two of you are holding hands, and other subtle physical ways of showing they care.