An easy fix for me, at least, was when I would lay out and try to get a full body tan, I would put tanning oil (SPF 4) all over myself, including my face and head.
Got tan nearly immediately.
If that doesn't work, give a tanning bed a try, it WILL work. You don't have to go constantly, but once a week or even twice a week will keep you looking tan all over, but not absurdly tan, just right.