I think one tip I have figured out is to not over-beat the egg whites, they get dry & do not hold the cake up! Be gentle when folding the beaten whites into the egg yolks… also, sift the dry ingredients into the egg yolks, lumps of dry ingredients are not your friend! When checking to see if the cake is finished baking, don’t leave the oven door open too long while you check the cake, don’t take the cake out to check it either! One tip is to listen to your cake, it should be quiet. This may sound funny but if it is quite it is usually baked through. The other way to check is to gently see if the cake will spring back if you push on it… if not bake for another 10 minutes