Find what you are good at. Find what you have a passion for doing. People will pay you good money to do the things that fit within both of these circles. No one is going to be willing to pay for your "C minus" work (or not very much). So forget about bringing your "fours" up to "sixes" (on a scale of one to ten). Focus on getting your "eights "up to "nines" and your "nines" up to "tens." (A bit of an oversimplification.. but you get the idea).