How to find people for user research
Talk to people who have dealt with the problem you're studying. ReacherX can help you find them and prepare a clear invitation.
Your friends may be happy to try your app. But if they don't have the problem you're trying to solve, their feedback can only take you so far.
For useful research, you need people who have dealt with that problem themselves.
Look for a recent experience
Say you want to understand how tutors arrange lessons with parents. You could ask ReacherX:
Find independent tutors who have talked about arranging lessons, handling cancellations, or chasing confirmations from parents. I'd like to interview people who manage their own schedule.
That gives you something more useful to look for than “people interested in education.” ReacherX can search X/Twitter and LinkedIn and help you inspect the people it finds.
Read the original posts. You may discover that the issue you wanted to study isn't the part people find difficult.