My methods have changed a bit since abandoning F2F for online, but they remain much the same.
I post on Reddit for replacement players, and besides the nuts and bolts points (time, day of week, nature and specifics of the campaign, etc), I throw in some of my house rules:
We are looking for a motivated player that is willing to make a commitment and put in the effort to make sure they are there for the game.
no PVP or theft from PCs or the party
no murder-hoboes
share the spotlight, work as a team
play your own gender
The next stage is to have an extended chat on Discord: gaming background (experience is not required), stability of schedule, and a lot on our expectations and what the player is looking for. Try to get a feel for a player's attitude. I generally do not accept college students because their schedule changed at regular intervals, and I've lost players that way. Go over my other house rules, which are basic things such as if you are eating, mute your mike, stay involved, etc.
If they pass that, I bring them into the Discord server supporting the game, and let them chat with the players, and take a look at out IC channel, handouts channel, loot channel, art channel, and the rest. If none of the players object to the new guy, he's brought in.
I then monitor him closely during the PC creation process. I recently cut two potential recruits during this stage.