I learned to bake at school and if I am careful about my method, I can produce a passable cake. The average German housewife, however, can turn out the most amazing creations at the flick of their wrist, so I don't bake many cakes myself in the face of such competition (I usually stick to shortbread, flapjacks, or mince pies at Christmas)
However, having said that, I recently learned something from a video on a cookery website. For a plain sponge cake you should beat the eggs and sugar really well, but don't overdo the beating once the flour has been added - in German it's called a Rührkuchen (a stirred cake) and you literally just stir in the flour with a wooden spoon with two or three stirs, until the flour is properly distributed.
I also separate the eggs and beat the yolks and the whites separately, stirring in the well-whisked whites right at the end - after the flour. This adds more air to make for a fluffier finish.
What is going wrong with your cakes? Are they just not pretty, or are they uneven, too solid, too soggy, too dry, wrong colour, not cooked right through - overdone on the outside and still gooey in the middle? Are they not rising? Do they not taste nice? Do they have a horrid fizziness that feels awful on your teeth? Are you sure your oven is really the temperature you set it to? Does the oven door shut tightly? Are you opening the door during baking?
The bland taste you describe can be improved by adding orange or lemon zest and/or juice. Ground almonds give a nice taste, too, or you could sieve some cinnamon or other spices with the flour. Or dissolve some instant coffee in a teaspoon of hot water and add that.
Practice, care, and following the instructions, as everyone else has said. And don't try to run before you can walk!