I dont think its good idea to wait years for an open slot. Sure, you can pick some popular artist or find an artstyle that you like and give it a try. If you arent sure ask for sketch before paying. But it depends what would you like. Many popular artist only draws 1-2 characters for high price. If you want group pictures or comics you need something else, maybe with compromises. Look around here, or on deviantart and check the profile info, check the gallery because the first few arts dont tell what the artist can or will make. Or check the art here and look up the deviantart link too.
If you find a less known artist, you can commission your art you want and get it soon.
My method would be:
1 good artstyle, who made it?
2 check gallery
3 check profile info and/or commission info
4 send a message
btw you can always check the artist that made the arts so you have a bigger picture who draws what and can look for them