Well I think there are only three main ways that really help on attractig members.
1. Be original. No one likes copy cats
2. Nice theme
3. Plenty if posts per day. If no one is posting, no one will join
Personally I don't think the software has anything to do with how popular a forum is.
Concerning SMF, it is a very easy to work with software, with a helpful communit, easy to install mods and more.
I am in the exact same situation as the OP. The difficulty is to attract members. Have had many hits today, but 0 registrations.
Followed the Quick Review advice on making forums viewable by guests, but I don't know if that even helps.
A community is as strong as its members. Content is as interesting as the ones members posts. Owners/admins/moderators can do just so much without an active membership.
Just get some unique features and tuns of publicity. Get the members who are already there to invite their friends, then they invite those friends, and so on-so forth.
Also, you need to professionalize your website by using proper grammar and spell check. We aren't all the best, but spell check does help.