Postaraj się in English:

Just do your best.

It doesn't matter if you don't win, just try to do your best.

All that matters in the exam is to do your best

You have my trust, so do your best.

Don't worry about your exam, you can only do your best!

You can do your best to buy natural products and to buy from companies that you have always trusted, but that is not always possible.

How do you encourage your staff to make an effort and do their best?

Please make an effort and talk to the other kids at your new school.

Do you make an effort to get a good passport photo?

You should make an effort.

You need to make an effort to meet new people.

If you make an effort, you will win.