Usually, word of mouth is one of the most effective for my website << url snipped >>. I tried creating promotions but they wern't very successfull at drawing in members.

It takes time for a community to grow and at most one of the most effective advertising for bringing in members is "word of mouth"

You can create modules such as a store where members have the oppurinty to use thier points to purchase items, whether it be a member feature or a materialisitc object (computer, palm, ect)