I agree with most of the commentary here about setting one up as soon as possible. As long as you have a few hours to set up your patreon, do it! A few dollars a month is better than none. I made like $10/month for a loooooong time! But lately, people who don't even read my comic have stumbled upon my patreon and supported me! You just never know.
Some tips: Look up patreons of people who do similar work to yours (and are successful) and check out their rewards and milestones to give you ideas. Don't be afraid to be flexible with your rewards; if they don't seem to be working out, change them. Ask patrons what they'd like to see from you.
1) Be sure to explain HOW patreon works somewhere on your site, since a lot of people don't really get how it works. If you can make it easy on potential patrons, they are more likely to help.
2) Be sure to explain WHAT their support does for you/ your art. Some people will support you simply because they want to support what you are already doing, but there are a lot of people who would like cool extras. Things like commissions, tutorials, access to exclusive artwork seem to do well.
(note) Choose your rewards well. Don't overextend yourself by offering monthly, polished, full-color personal commissions for people pledging $5 -- that's easily worth $30+. You want to offer cool rewards and extras, but if this is primarily for your comic, you want to make sure these extras won't cut into your actual comic-making time.
3) Break up your text with pictures to avoid the daunting wall of words. If you can, upload a video. It's not as necessary as it is for kickstarter, but it can work well. I know people who are very successful on patreon w/o a video, so don't worry yourself first off about it.
As for audience? Expand your reach! Get active on twitter, tumblr, etc.
And don't be too disheartened by someone who has fifty thousand subs on tap but gets two dollars monthly. I know people with much lower subs that get hundreds monthly thru patreon. The sub numbers on tap don't mean much in terms of patreon; you don't know what kind of outside promo those people are doing!
A final tip -- for high tier rewards, like commissions and tutorials, release that content after payments are processed. You very well may get pledge-and-drop patrons who pledge in that tier to get the reward, then pull out before the payment is processed. Sounds sad, but it's true. It happens.
Good luck!
