This is the best way I have managed to explain these things though to be honest, I wouldn't really worry too much about grammar. We can still understand you anyway!
Thank you, but I am perfectionist sometimes
Comma: A comma acts as a punctuation mark that can do quite a lot of different things but it tells the reader when to have a pause. The easiest way to know when to include them is to read what you have written and see when you naturally stop for a breath and this means that some kind of punctuation is needed.
There is a big problem: "rhythms" of speaking (I cannot find better words) in Russian and English are quite different as for me. That's why Russians are surprised often when they find comma in "unexpected" place in English text.
If it not the end of a sentence then a comma is the most common thing to use (though of course it could also be semi-colon, colon, dash etc.)
When would you use a comma?
-To separate different parts of a sentence such as "He tripped while he ran, then fell, then got up again."
-Before a short conjunction such as but, yet, and or so (the comma should be before the conjunction) such as "It's cold, and rainy."
- For an introductory section to a sentence such as "However, it was still very fun."
-To insert a part of a sentence that could be removed but the sentence still making sense such as "Yellow throated martens, which have yellow throats, are carnivores" (a comma around each side of the inserted section is needed).
Good examples. The first and the last ones are completely similar to Russian rules.
Third example is not quite right in my language: we have complicated rules for "introductory section words" and "linking words" (which are often the same, but we must use different rules in different situations), and Russian word "however" should not be separated with comma in the case mentioned above.
Second example is very confusing. We use comma always before "but", but I often see that there is no comma in such a case in English texts, and I don't know is it correct or not. The word "and" is used in the strange way too

. We have many rules for using comma before "and", but English-speaking (-writing) people use it more often as for me. For instance, there is very usual phrase type: "first, second, and third". We do not use comma before "and" in such a case.
So for me conclusion is: rules are mostly similar, so I should use Russian rule until I know English
This is a very extensive explanation of comma usage, I don't think you need to really bother with all this as we can understand you anyway but you asked so I have explained.
Overall, I don't really think you need to make your grammar perfect, we can understand you anyway. However, if you want help, I am happy to help and I'm sure others will be too. Remember, though, that even native English speakers who don't speak any other languages make mistakes (people constantly misspell a lot as 'alot' or 'allot', it is two words by the way

)
I have to converse officially sometimes, and any comma could be important. Besides that, I think that a good language is a kind of respect for interlocutor.
Please correct my new mistakes!
