The Optimization and Promotion of Adult sites is same as you do with normal website. The only difference is that when you are promoting Adult site, then do all the SEO Activities with Adult Sites and in Adult Category only.
To be honest with ya, most people who optimize for the adult industry are black-hats. If you can compete with them, you will get the results.
It's hard to achieve good result in SERP when you work in adult industry. That's right - there is a lot of black hat seo but still they build many websites and link between them.