I was just wondering what else do you use to keep your cake moist or make them moist. I was going to try coffee creamers with different flavors but I am not sure if it is good idea or not.

Honestly? Find a good recipe and don't overbake it. Your question to me could be interpreted a couple ways.

1. Your cakes are actually just fine, but you're trying to acheive that cake mix moistness (which in reality is just oily, not moist).

2. You're overbaking perfectly good recipes.

There's a couple other things too that may actually be a remedy before going the route of adding moisture post baking.

Exactly what AZ said. And if you still want to adjust your recipes after that, you can add sugar and/or oil.

All of the above. A great recipe is balanced and has the correct amount of moistness. It shouldn't have to be added.