My GFR is 22. How do I improve this?

If it can be improved, it will depend on what is causing it. Your nephrologist is the person you need to be asking these questions.

You sound like you are in a country where blood tests results are given to patients without a doctor's review, and where many people don't have a regular doctor for repeat visits.
If you don't have a kidney specialist, you need to find one, or a large clinic.