Players you don’t know personally online are prone to being flaky when it comes to showing up for sessions, at least until they have become personally invested in the campaign and the GM.
Here’s a great tip to counter this I found on reddit:
One way I’ve found for helping to eliminate flaky players, encourage others to GM, and make them appreciate the effort that goes into preparing a session is that I will make the players do preparation themselves or have homework assignments.
Between sessions I will ask them to help shape the world by telling them to make up details about the various factions, cities, areas and such. It has the added benefit of getting them more invested in the game as well. Other times I’ll ask them to write up a story from their characters past, or a few paragraphs of internal monologue from their characters point of view on how they secretly view the other characters. Or make them keep journals.
I tell them that the next session doesn’t happen until their own prep is done. It makes being a player a much less passive activity. Even better I’ve had this player preparation spur a few of my players into the GM seat since it seems to kindle a desire for world building.
Well either that or they are sick of the extra work from my games and GM to avoid it. Either way it’s a win win.