How to say in korean "give me a piece of advice" or "advise me, please"?
and how to say "to follow sb.'s advice" in korean?

Question

How to say in korean "give me a piece of advice" or "advise me, please"?
and how to say "to follow sb.'s advice" in korean?

Answer

You can say 
조언 부탁드리겠습니다. = advise me, please.
조언 해주세요. = advise me, please.

You cannot translate "a piece of advise" to Korean exactly. It will be awkward.

Answer

Advice in Korean language is 조언 (Jowan) or 충고 (Jungo). Advised in Korean is 조언하다(Jowan hada), 충고하다(Jungo hada), 권고하다(gongo hada).
https://koreanly.com/advice-in-korean/

Answer

제가 의논할 사항이 있는데 좀 도와주시겠어요?

의논하다 = to seek advice
사항 = matter
도와주다 = help

I would say it like this.