We use a number of different methods -- all fo them mentioned in the unit. Th emost helpful have been the following: professional organizations, networking and targeted, specific ads (with specific dealbreakers). By far the fastest, and best for finding new, local adjunct faculty memebers is at professional networking events -- the folks there have the qualifications you are looking for, may know you already, and may knwo something about your organization -- some of our best prospects, who turned into great instructors came from jsut being open at meetings.
Recently I had good luck with a very targeted ad, which included a number of dealbreakers -- only people who matched the qualifications applied, so the pre-screening was done. We only got 5 responses, but two are teaching next term.