I was shown how to clean ears by the vet, when Jonny was a pup and had ear mites. With the cleaner I had then, you scoosh some into the ear, massage for a few moments, then clean out the result with cotton wool. Unless your fingers are absolutely tiny, you can't go far enough into the ear canal to cause damage, especially as the finger is wrapped in a ball of cotton wool. Nowadays, since neither dog actually has anything wrong with their ears, I just moisten the cotton wool and folow the same procedure. There's usually some wax there to get out.