To learn from someone's excellent example; to try to imitate or gain something from a person admired for their virtues or skills (idiom).
先輩の仕事ぶりは素晴らしい。爪の垢を煎じて飲みたいくらいだ。
My senior works wonderfully. I almost wish I could learn everything from them (literally: boil and drink the dirt under their nails).
あの先生の指導法は参考になる。爪の垢を煎じて飲んででも学びたい。
That teacher's method is worth studying. I'd learn from them even if it meant 'boiling their nail dirt' (i.e., copying exactly).
彼女の節約術は見習うべき点が多い。爪の垢を煎じて飲むつもりで聞いてみよう。
Her saving habits have many points worth emulating. I'll listen as if I intend to learn every little thing from her.