I think the big thing is keeping scammers out while not blocking legitimate users.
I have been reading comments on this site and lots of people seem to get locked out of their profile for one reason or another when they are an actual user who wants to find a date so there seems to be a lot of false positives on dating services were they think they have found a scammer when they actually have not.
The only way I see this is to enforce some sort of live photo verification and some sort of id check.
The other problem is hacked accounts because some legitimate users have really bad passwords. The dating site needs to enforce strong passwords and maybe include 2 factor authentication so when they log in a code is sent to their phone that they need to enter as well.
These 2 things are important to any dating site design.
I’m a big fan of Match.com and I feel they do it pretty darn well. I’m not sure on what to improve except maybe cost? You can get a decent amount out of it for free though as long as you go with the mutual match suggestions.
I wish they could somehow verify and vet people before you get on so you know up front if people are fake and scammers. But, just like the real world you need to figure it out yourself.