Best Practice for best Normal

Hi.
I am currently studying to become an artist. But I have some difficulties in getting good normal map. I did ask my tutors, but I think they are too busy, and the training dates back to 2010 (online). I followed many tutorials on YT, and I asked my questions on forums, without answer, but now, I do it here.

I have rehearsals of parts like ears. Could you help me?

Thank you.