So here it is, I have not told anyone until now but this is something I read over ten years ago that works for me. "Cakes by Design," by Scott Woolley, a cake designer in NYC wrote this in his book. After removing your cake from the oven, run a knife around the edge and let cool five minutes. Cover with plastic wrap, then place cookie sheet or cutting board on top (I use a cooling rack bigger than the size of my cake) and flip it over. Lift pan slowly as it releases fold plastic wrap up over cake, sealing completely. He wrote, many a cake becomes dry by cooling on an open rack where it looses moisture.
I set my timer and do not go over 5 minutes for any cakes including heavier ones like carrot and lighter ones such as a white cake. I then place the wrapped layers in the fridge to cool from three hours to overnight, then I fill and frost. Let your cooked cakes sit in the fridge longer than overnight and you can dry them out during this step also.
I was busy making eight tasting cakes once for more than a few, soon to be married couples and could not keep up with the cakes that were cooling over the five minutes. I delivered the cakes finished to the catering company whom I make a majority of wedding cakes for and after the tasting the office girl wanted to let me know for some reason my cakes were fine but not as moist as usual. I was mortified and have never wavered from this method since.
Please keep in mind another big reason cakes are dry is from overcooking. I cook my cakes about 25 degrees less than suggested, they take longer but come out moister and more level for me. I watch mine like a hawk and when they start to pull away from the sides of the pans and spring back to the touch I immediately take them out to cool. If I have any question, I sometimes use a toothpick in the center and it should come out dry or with a few crumbs stuck to it depending on the recipe I am baking. I hope this helps you like it has me, good luck!