I often see some Japanese phrases that are grammatically correct but unnatural in terms of cultural context.
Here are some of them that are frequently used on some language learning sites or apps.
It literally means “please give/lend me a hand,” but it’s not common when you ask someone to teach or advise you with something.
It sounds like “do something instead of me” or “share this work with me.”
So, when you want someone to do some of your homework, ”手伝ってください”（てつだってください） is perfect.
In the case of language learning,
(にほんごをおしえてください) = Please teach me Japanese.
(にほんごの がくしゅうを たすけてください) = Please help me learn Japanese.
sounds more natural to me.
Many Japanese learners write this phrase at the end of a request (like “Please do this for me. Thanks!”).
This phrase, however, is usually used for someone doing something for you,
so it’s too early to say that when you ask for a favour, especially when you haven’t received their answer yet.
You can say ありがとうございます when you get a positive response to your request, even though it is before they have done what you asked for.
In this case, ありがとう is for accepting your request.
Before getting their response, you should say “よろしくお願いします” (よろしくおねがいします) , which basically means “please treat it (me) nicely.”
[Before getting corrected]
(てんさくおねがいします。ありがとうございます。） ≒ Please correct my entry. Thank you for doing that.
（てんさくよろしくおねがいします）≒ I’d appreciate your correction.
[After getting corrected]
（てんさくありがとうございます) ＝Thank you for the corrections.
FYI: To make them more casual, you can omit “ください,” “ございます” and “お願いします”.