... have the place staffed by volunteers too, ask visitors their hobbies or subjects they know about, help them find topics they are interested in and help them to dip a toe in the water.
Invite them to watch skilled editors at work who are open to questions...
Invite people to take good quality photos and bring them in to be touched up and show them how to upload them to a holding area with the best going into Commons (saves issues for the many pics that just won't make it, they can still learn!)
Engagement, in other words
FT2