1. mouth-2-mouth through friends.

2. This is a bit cruel... Find a post on "other" forum which haven't got any answer. Create a new thread with an account containing the same question but paraphrase the question (make it similar). Then use another account and answer the post. Then, post a link in the "other" forum to your forum (which contain the answer). just hope your link will never be censored.

3. Search engine