When to use 手 and when to use 家 for a type of musician or other specialist
钢琴家 is not just any pianist; s/he is a piano virtuoso. I would reserve this for someone who has a career in music, especially in performance; or someone who has attained a very high level in the art of piano playing. 家 can be translated loosely as "an expert in ..." So you definitely do not use it for yourself. 手, on the other hand, can be used more generally for someone who plays a musical instrument.