You could hire someone to proofread your papers, and there are some online services that help with this as well, but I have not used them.
If you are trying to improve your English on your own, I suggest working on one issue at a time. For example, first, spelling, but beware of relying only on spellcheck. Second, common mistakes such as mistakes with:"to or too" and mistakes with contractions "their, there, they're" "its it's" "your you're" and with agreement between noun and verb tenses and use of the correct articles. You can find online resources to explain these simpler rules.
When you get to more complicated types of mistakes (grammar tenses, organization, etc), you may want to turn to in-person or online tutoring, with a focus on writing.