If you have just installed Mastodon and don't know where to start to find people to follow a good idea is to try and check other users follows and one by one try to see if you find someone to follow.

Alternatively you can go to https://communitywiki.org/trunk and do the same on the categories that interest you.

If you are lazy and don't want to look up one by one, I created a little script to generate a csv from Trunk categories: https://hugo.gameiro.pt/trunk-to-csv/ that you can then import in Mastodon.