How to Deal On Craigslist

I design logos and search craigslist for anyone who is asking for one, but im not sure if I should do the work first with the risk of not getting paid or asking for half the amount up front. I am also contemplating sending a link where they can order my work from a gig site with a bit more assurance but then they have the aggro of registering with the site first.
Whats best?

Make a website displaying some of your work. Ask for half up front (or when you send the first round of logos) and then half when you are done (deliver final .ai or .psd)

Get a verbal / email agreement to pay if you can't collect at least 30%. Design their logo with SAMPLE all over the place and collect payment in full BEFORE handing over the high-res versions without SAMPLE on it.