Pay attention to the ratios and weights of ingredients and make sure you follow the recipe: too much flour or too little fat will increase the risk of dry cake. Baking the cake for too long is also a culprit for dry results, so keep an eye on the clock.
Many bakers regard coffee as the secret ingredient in the most intense chocolatey of all chocolate cakes. A little goes a long way and too much could change the flavor profile from pure chocolate to a distinct chocolate-coffee combination. A teaspoon of coffee powder, added while mixing the dry ingredients, should do the trick.
Poor quality chocolate is one common reason for a lack of flavor, so try swapping for a more cocoa-rich brand. The coffee trick, as well as an extra touch salt, can also help to increase the chocolatey flavor.