i enjoy singing myself and considered it but i simply have a lack of technology skills.
but perhaps you can learn, is my suggestion. i know that sounds unhelpful, but its so convenient to be able to do it yourself. why not find and pick a free program and look it up? i might reccomend the free program Audacity, as i used it in high school. audacity also has a very detailed almost wikia-like FAQ on how to use it for almost anything. you should also be able to YouTube search live tutorials.
i hope i could be of some help! good luck in your quest!
Oh my when I saw the title in my mailbox (Have wikia notifs), you shocked me XD //sorry off topic orz...
I'm not sure, if there are some people on YouTube willing to take on mixing requests... So well I kind of think, that you might want to try starting out small with trying to mix your songs yourself with audacity or such, so your first videos probably wont be so well mixed, but as you get into the community, you'll happen to find friends, and if you're lucky, they might even be mixers ;) But don't try to make friends just to get a mixer （ಠ_ಠ）.
I guess a good way to interact with other YouTube singers is also participating in some choruses? Try asking some chorus groups which don't have fixed members maybe? o.o