1. 

A good way to find friends, believe it or not, is by finding people who also want to find friends (who knew :P). A really good way to do this is by going to the 'friends' forum and sorting it by recent topics. the following posts will be somewhat recent posts with little to no comments (CAUSE NO ONE USES FORUMS!) usually made by people looking for friends, so it's a good place to browse. You can also do this, but in forums that revolve around a topic you're interested in, if you want a less broad option.

2.

There's a feature that, as far as I know, was active for a bit, but isn't anymore due to it being broken. This feature is the 'advanced search' option in the search tab, and even though you can't use it I think I found an alternative. This will clog up your search history, but you can kind of just search a few words pertaining to your interests and add 'spacehey' after it. You will find profiles with people that have these keywords in their profile (presumably cause they like said thing), but this is far from a perfect method due to the fact that it's very likely the accounts that show up are older and inactive.

3.

Do it the old fashioned way! :D. I personally think that its fun to go to the browse tab, and look through whatever profiles catch my eye till I find someone intresting. it takes a while, but personally I think this is actually one of the best ways to find other people to friend.

4.

imo this is kind of a last resort option (not that there's any shame in it lol), but something a lot of people like to do is post their spacehey URL on off platform sites. I'm pretty sure the most popular place to do this on is the spacehey reddit, but obviously you could do it anywhere.