I suppose the "How do I" question here would be how do I make a good cake? I'm not asking for a recipe or secret ingredient but if you thought a particular cake was great what made it so great? It seems like the answer would be beyond "moist and fluffy" like maybe only really excellent cakes have a unique taste or something. Also how does one experiment and come up with his or her own recipes if one is supposed to follow recipes exactly?
AThe 1st time you make a recipe it should be exact so you have a basis for comparison. To make any adjustments after that you should have an understanding of the science of baking.
"Good cake" is hard to define because everyone's taste is different but I always know I've done well if someone says to me "I don't like cake/frosting but I loved yours!" If your cake is just plain good, people will notice.
As you get more familiar with playing around with your recipes, you'll learn what you can tweak without affecting the science behind it. Try starting with a basic recipe (white, yellow, chocolate) and experiment with using different extracts in place of vanilla. Lemon and orange zest can be added to or removed from a recipe without affecting the science of it, only the flavor. Try using cream instead of milk. Little things like that will alter the taste and texture of your cake without hurting the actual cake.
I take a very French approach to scratch baking and cooking in general. Taste is paramount. It doesn't have to *look* perfect, but it must taste awesome. For me, I don't like light and fluffy cakes. I like my cakes denser with a tight, fine crumb. It should be substantial. You have to think, wedding servings are tiny and I want the most bang for my buck if I am getting a super tiny piece.
AI love using almond extract for white cakes. For chocolate cakes, I add in some instant espresso (or espresso powder). A teaspoon enhances the chocolate cake and using more gives it more of a mocha taste.
I'm not picky about my cakes, but a really good cake is rich and smooth and practically melts in my mouth.