This might be a bit pessimistic, but I think looking for art based solely on the promise of future pay, whether that's revenue share or a future crowdfunding campaign, is generally a losing proposition. Most artists that you would actually want to do art for your game wouldn't bother with a situation like that, and most that would aren't any better than you could be with the help of a few tutorials and a couple months of practice. I know financial constraints are hard (often impossible) to work around, but considering you aren't doing this full-time, it'd almost certainly be more beneficial in the long run if you either saved up money for a few months to hire an artist, or spent those months practicing your own skills.
As for Kickstarter/Greenlight, read this:
Lobster Sundew's Kickstarter Guide
Read all of it, and take a lot of notes.
The most important part of the Kickstarter, maybe the only things that matter, are the art and music in the trailer. Everything else is necessary, but if you lack a trailer with some real verve, you're in trouble no matter what's underneath it. Make sure you get a lot of feedback on your trailer, and if you have the luxury, make sure that it's overwhelmingly positive.
In an ideal world, you'd be able to do a PR/marketing rush 2-3 months before you launch your campaign. If it sticks, you know you're on the right track. If you can't get any traction from media outlets, you should definitely reexamine your approach. It's a rare Kickstarter that gets its audience after it launches.