Tweethere's a few pointers
1. make your URL's seo friendly. For example, this thread URL should read https://www.fitnessgeared.com/google-adsense.html
2. create a sitemap and submit to google. https://www.google.com/webmasters/
3. Link back, link back and more link back. Getting other sites to like to you gives you relevancy.
4. anchor text keywords - fitness geared for example, you own this keyword on google. if you type this keyword in, you come up first. make a list of keywords that you want your site to come up for. fitness diets, fitness workouts, fitness forums are good keywords to optimize the site for. Use these keyword with rule number 3, link backs.
5. Blog post and website reviews. Find 'fitness' related blogs to write a review about your site. Use your keywords from number 4, to create text anchors and link backs in the reviews.
Your efforts should go on getting your site listed on google, yahoo and msn. organic traffic is better for your site and cost you nothing. Pay per click will cost you more, but is more targetted. Unless you're selling a specific product, I wouldn't go with PPC.
Here's a site that does vbulletin seo optimization. The other board I frequent uses them with great success. https://www.crawlability.com/vbseo/