Forget what you know about marketing and start from scratch. The adult industry differs from mainstream marketing in quite a few ways.
Be prepared to work hard. Especially initially. You need to set up a network of sites, once it’s up and running it just requires maintenance.

Tips:

Use blogs
Google likes blogs…it’s no coincidence that Google recently bought Blogger.com. I use weblogs extensively. That gives me a lot of targeted search engine traffic. Well-constructed text links work wonders. You’ll see many sites with for instance the phrase: “click here to see tight teen pussy”
All very well, but the mistake they make is to link the words “click here”
(Go to google and type in “click here” and you’ll see how many results will turn up)
Much better would be to link the words “tight teen pussy”, that way the search engines associate the words “tight teen pussy” with your link. Added advantage of linking a phrase rather than a single word: in this example, you get the hits for tight teen pussy, teen pussy, tight pussy, and pussy.

Webcams sell
Everything interactive, in fact. I do very well with webcam sites and dating sites.

NEVER spam
Spam is against the Terms of Service of most sponsors, and also most web-hosts. If they get spam complaints, they’ll terminate your account.

Use Dynamic content
Make your content dynamic, if you can. Many sponsors have rotating galleries or pic-of-the-day sites, this gives the impression that your site is updated daily. I also use PHP to dynamically change pics…check out www.sex-startpage.com for an example. (hit reload a couple of times)

Use text-links
People don’t really click on banners any more. Rather use a good text-link describing what they’ll see if they click. And TELL them to click…surfers are stupid. If you don’t tell them to click, they won’t
A well-constructed text link does 3 things: it piques the surfer’s interest, it tells him what to expect from the site, and it tells him what to do.

NEVER steal content
There is no such thing as public domain. Use the free content provided by sponsors. If you really want to buy content, Reyko is very reasonably-priced.
If you don’t feel like paying for content, many of the sponsors listed on this site offer free hosted galleries for you to use.

Use .htaccess
I have the following htaccess file on most of my domains:

Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} !^www\.domain\.com
rewriterule (.*) http://www.domain.com/$1 [R=permanent,L]
ErrorDocument 400 http://www.sex-startpage.com/
ErrorDocument 401 http://www.sex-startpage.com/
ErrorDocument 403 http://www.sex-startpage.com/
ErrorDocument 404 http://www.sex-startpage.com/
ErrorDocument 500 http://www.sex-startpage.com/

The first part makes domain.com the same as www.domain.com. That way you get the same Google pagerank for domain.com and www.domain.com…it sometimes differs. (of course, you need to substitute “domain.com” with your own domain name)
The second part redirects all my error traffic to www.sex-startpage.com
It’s amazing how much traffic you’ll retain if you do this, much better than surfers ending up on a standard “page not found” page.
Depending on where I currently want to send my traffic, I regularly change what’s on www.sex-startpage.com

Use FPA’s
Most sponsors provide you with Full-Page Ads. Instead of linking directly to the site you’re trying to sell, it’s better to link to a full-page ad for the site. The reason: say you have 10 domains, and on all of them you have links to for instance fuckspy.com. This will cause search engines to associate those links with fuckspy.com, and put it high on the list of search results. It probably already is at the top. When you rather link to the FPA on your own domain, you can then optimise the FPA for the search terms of your own choosing. That means that when a surfer types in “fuckspy”, he will see the official fuckspy.com site as first result, and (hopefully) your FPA as the 2nd, or at least on the 1st page. Added advantage: you can put something like “No thanks, take me to www.yourdomain.com” at the bottom, in this way you retain some people who would have just closed the window otherwise.

Customise your FPA’s
The FPA’s that sponsors provide are usually just one big graphic, like this standard fuckspy FPA. As I said before, it’s better to use text-links. Here’s my custom fuckspy FPA. Using text rather than graphics, and alt-text on the graphics you DO use, you can now optimise the FPA for search engines, using the keywords of your choice.

Some myths:

TGP sells.
Yes and no. To sell well using TGPs, you’re going to have to invest a lot of time and effort: firstly in just learning the TGP biz, secondly in building and submitting galleries on a daily basis. The top TGP people like Sleazydream, The Hun and The Shemp have massive amounts of traffic. The Hun gets a million unique visitors per day. That’s more in monthly bandwidth bills than I make in a year. Stands to reason that you have to be really good to still make a profit after that.

Teen is the hottest niche.
The “teen” niche is the hottest, but not because it sells best, just because most adult webmasters promote it. In fact, it’s probably the most difficult niche to sell, as it’s totally over-saturated.

You need lots of money to start.
I started with nothing. I signed up with a free adult host, using free sponsor galleries, and moved to paid hosting after a month. I never invested a single cent of my own.

You need a dedicated server.
Nonsense. I use a virtual host ( the “dork” plan at www.nakedhosting.com starts at $4.95 per month: unlimited diskspace and bandwidth). I use the “geek” plan and it’s more than I need for my 40-odd domains.

You need lots of live feeds and need to update your sites with exclusive content regularly.
Live feeds are expensive. I use some free live feeds provided by sponsors, sponsor hosted galleries with their free content, and very little content that I bought. I make money off it, so can you.