Thank you for pointing out my mistakes! Thank you for pointing out my mistakes!

Your use of the exclamation point here is correct, however we don't typically use it so many times in the same post unless we are very excited lol. Using it so many times in your paragraph gives the impression that you are bouncing off the walls with excitement lol.

Thank you for pointing out my mistakes! Thank you for pointing out my mistakes!

I study Englis one more timeam practicing my English again today. I am practicing my English again today.

From context, I infer this is what you actually mean. Using "one more time" in this context implies that it will be the last time, or that you're giving something a second chance after a bad experience the first time, or that you're doing something "one more time" even though you know you should stop and do something else for a little while (a common example would be children asking to play a game just "one more time" before going to bed).

I studyieuse Englis one more timeh again. I studieuse English again.

Today is on Friday! Today is Friday!

Things that you do are "on" Friday. Today has the property of being Friday, so you don't need to use a preposition.

I love Friday, becoause tomorrow is my day off. I love Friday because tomorrow is my day off.

I'll do my best at work! I'll do my best at work!