Advice needed about players with commitment issues

Hi After meeting now over 10 players in a row who have seemingly severe commitment issues, I'm wondering how to handle things best and thus this post for some advice. Normally I go along things this way: 1.) A player tells of his interest in a game of mine 2.) I talk with the player and pm him what concept and background of a char he has in mind 3.) If it fits I send him an invite and talk with him (and also tell him again that my games are more focusing on story, thus we have a slow pace there because of that (not a 1 adventure per session thing). 4.) I help with the char creation where needed and then check his submitted background and charsheet and tell him what needs to be changed so they fit...and that the char is realistic in the universe. Most of the time I also postbone a session if its currently at a good state to introduce a new char in order to give the player a chance to start immediately. Thus 1 week or 2 weeks postbone there. Depending on how often that game is being run. Now I'm used to people finding out after 1-2 games that the games are not what they want (that is no problem). Other people have problems with their character concepts being criticized and quit at that moment when I say that and that makes no sense (gets on my nerves a bit, but whatever). What really ticks me off is, that it seems more and more peopledon't even go to step 4 but instead at step 1-3 they suddenly stop responding or they suddenly say "sorry I can't commit myself to a game". Had that now 10 times in a row in one game and over 5 times in a second and that in 3 months. And most of the time I even made the error to postbone a session. What I do nowadays is remove the contact of the player from skype and block him here, but tbh those players probably are doing that behaviour left and right. So I'm wondering 2 things there. 1.) Is there anything I can do to lessen the chances of players with commitment issues even trying to apply to my games? 2.) Is there anything that can be done so that other gms are not falling for those players either? For 1.) Is it maybe better to actively seek for players (through the directory) instead of putting up a "game open looking for players" post?

For both the answer is "no". There is no rating system on roll20 as far as I'm aware and the "recently played with" section is not publicly visible.  I was playing with a beginner GM who at the end asked the group how was his GM'ing and I really enjoyed our game, I rated him highly in the forum topic I made in which he contacted me for the game, but that got buried fast. I was thinking about making an outside webpage for something like "Rate your GM" or "Rate your players". In case of your last line, yes. I do think it's better to look through the player directory and check what the players have written in their "bio" section in their profile. As it does seem that people who care are more likely to actually spend some time filling out that. And you can learn a lot about the player even before you contact them. The downside to looking through the player directory is that you never know if the player is still active (you can check his activity on the forum, but that won't tell you if he's definitely still active), which you'll know right away if someone applies to your game. I actually had a GM find me in the directory, contact me and in the very first line of his PM he thanked me for listing the times I am available to play in my "bio" section. 

You should never postpone a session for a single player. Postponing a session puts the rest of your players out and likely will cause them to start looking for other games while yours is postponed. Unfortunately, there's no method of determining which players are going to flake, and it's unlikely that there will ever be a rating system, as there's heavy potential for abuse. You just have to search around for players, and sometimes you get lucky and manage to land people that are willing to commit.

Unfortunately, there's no method of determining which players are going to flake, and it's unlikely that there will ever be a rating system, as there's heavy potential for abuse. Meanwhile GM's and other players have to suffer the abuse of the flakes.

Unfortunately this is an age old problem that has no real solution bar the obvious, only game with people you know or people you know to be reliable. The same goes for face to face games although the pool of players is somewhat smaller and easier to vet. In answer to both 1 and 2 of the OP's questions: To ensure you have a group that is trustworthy, reliable and a good fit for your personality and play style I highly recommend running or taking part in many one shot games, find people who you get on with, people who play how you want and do so regularly and then form a long term game with those people. Even then there will be times when people 'flake' but that is often an easy term for a complex problem, real life is unpredictable and those players and GM's who suddenly drop off the face of the earth may be dealing with real life issues that are far more important than gaming and while common courtesy would dictate that they could at least let their group know it may be the simple fact that it just doesn't occur to them in that moment. Of course there are people who are just plain flakes and they are no different to those people who agree to go to the movies and then never show or offer you a lift somewhere but forget to turn up and boy is that annoying but it is just how it is. A rating system would go some way to helping with it but it would also alienate some people who, through no fault of their own, have been unable to continue a commitment and received negative 'reviews' because of it not to mention the trolls out there who would revel in destroying someones chances of getting a game just because their character didn't get a magic item in one game they shared with player X. We are lucky with the community here, I've never encountered one that is so full of helpful and dedicated people and while there are undoubtedly some 'bad eggs' out there they tend to not last long as they usually don't have the staying power for TT gaming. Stick it out and find that golden group, trust me, it's out there!

Yeah, if I was planning to set up a campaign with strangers, the first thing I'd be doing is getting one-shot modules (maybe 4 encounters long or one major map in size) and running them for people.  Then you actively invite back the people that weren't flaky until you get something more stable. No "World's Largest Dungeon" first cab out of the ranks.

Andrew has it right, you can't expect strangers to care when they don't know you. People have staying power when they get hooked on the story. So maybe an initial one short to get to know the characters is a good thing 

Ok, while this relates to Roll20 in terms of finding a good group it is essentially a social issue and therefore outside the realms of expected use for these forums. I've allowed it to run in order to garner some useful information for the OP and as per usual the community have obliged in force. There is little more to be said so further discussion of this subject matter should be taken to other places more suited for generic group finding help (maybe  reddit ?). In summary, the internet is full of flakes but also full of genuinely awesome people, finding them can just be tricky. One shots help a lot with finding those diamonds. The key to success is networking when playing via a network :) Good luck with all future groups and may all your rolls be 20!