I am also not a native speaker but have studied Japanese to a good level - and my native language is Korean which has remarkably similar grammar as Japanese. First off, not using "you" is more for when you speak with people you're unfamiliar with because you don't want to be rude. With people you are close to, you are less careful so you can say anything. Who one is talking about is usually clear from context, and it has little to do with a particular language. Let's say I'm talking with my friend of mine. I say "Saw the XX show last night?", or "Stopping by the bank this afternoon", it doesn't matter if it's Japanese or English. It is pretty obvious that I'm asking him in the first sentence, and talking about myself in the second. The context takes care of a whole lot, and when there is ambiguity, you might still get by without adding the subject by changing the intonation, rephrasing the sentence slightly, and so on. About the sentence "I would like you to help me with Japanese please.", my first try would be わたしの 日本語 べぇんきょうに おてつたって もらえませんか？ or わたしの 日本語 べぇんきょうに おてつだいにl なって もらえませんか？ ( these may not be perfict - but it shows an example of no subject sentence) The "って もらえませんか？" is a fairly common expression for "I need you to...". It is literally, "may I receive (your) doing so-and-so done (for me))?". So it is more respectful than くれませんか which means "do/give/etc me so-and-so".

Yes, coming to grips with not using あなた　as freely as we use 'you' in English take a while when learning Japanese! It simply isn't possible in English to ask "can you help me please" without including both 'me' and 'you' in the sentence. But in Japanese, it seems to be quite common - and indeed, preferable not to use the personal pronoun. So how does that work? You can say 日本語を教えてくれませんか。which means 'won't you please teach me Japanese'. [This may not be the most refined or elegant way of asking in Japanese, and I am sure a native speaker could suggest a better way, but for purposes of illustration, it will suffice here]. This is also a very good example of the wonderful way Japanese make compound verbs - 教える　「おしえる」means to teach, tell, or show, and the verb くれる　means to give, but not just 'to give' generically, but to specifically give to the speaker, so it is obvious that the giving being requested is to you, from the other person. As you are talking directly to them it is obvious that it is from them you are requesting the assistance - if it was from a third party, you would name that person by saying that you want Tanaka-san to teach you Japanese. This is a good example of where we can't just form an English sentence and go about translating it directly into Japanese, because then we want to put the 'I' and 'you' in there. But if we take a step back and ask ourselves, what am I trying to say here, then look at how Japanese expresses those ideas, we can come up with a solution. It isn't easy, and it takes practice, but being aware of the pitfalls in the first place is a good start. Hopefully that addresses the request for an explanation in English! I will leave it to a native speaker to suggest other ways of expressing it in Japanese.