Tips for effective everyday writing:

It is important to show

certainty in your writing.
글쓸때 확신감을 표연하는게 중요합니다.

Starting a sentence with "I think" and "maybe" probably shows more uncertainty than politeness. "I think" and "maybe" should be avoided if possible.
문장 앞에 'I think/maybe" 쓰는거는 예의보다 불확신감을 표연하는거다. 될수있으면 "I think/maybe" 안 쓰는게 좋습니다.

❌"I think there is a quality issue with the merchandise maybe."
⭕"There is a quality issue with the merchandise."

In business English, you should definitely not say "it will be difficult" when you mean to say "it cannot be done."
비지니스 영어쓸때 "힘들겁니다" 보다는 "못합니다" 가 더 난 표연입니다.

You should never use "etc." If it's not important enough to list, it should not be mentioned with a "etc."
"etc." 쓰지마세요. 나열되지않은건 중요하지안은거래서, 언급도안하는게 좋습니다.

❌Our machines are the 3500t press, 2500t press, etc.
⭕Our machines include the 3500t press and 2500t press.