I tried out a local running club, once. It was a nightmare to find, spent a lot of time trawling the net to find it.
I would say putting out flyers and posters locally, a spot in a local newspaper, it would be good if club members wore t-shirts out on runs, means a local runner might strike up a conversation and ask more. A lot more information on a website would be good, it was near impossible to find clear information about where the next meet up of my club was. It makes it feel quite elite to newbie's if they don't know a member to ask and the information isn't readily available.
It helps if there is more of a beginners "section" and that is well publicised. It was a bit daunting for me when I showed up and was told I was about to spend an hour doing hill sprints with blokes that had being doing ultra's even when I made clear my abilities before I arranged to go to a meet.
Maybe offer to do a bit training with beginners, make it quite relaxed give them a cheap club goodie bag after a couple of weeks? T shirt and gels? Wristbands?