well, for starters, I opt in adword with budget optimizer ($1/day - 30day cycle)
I have an increase of visitors within the first hour. for my budget of $1/day, I finished it up within 3 hours. lol..seems like I got myself a good niche.
According to adword gurus, you will see some improvement on your traffic using adword, and together with SEO product such as vbseo, I wonder if it might get me more members.
Now, I just wait for the traffic to convert into signups.
I highly recommend using adword. You just pay when someone click on your ads.