One frame only: This type of tour needs to fit into only one screen, which is to say that the whole presentation appears on screen without the user having to scroll down or across. Again, different users have different screen resolutions but the most common today is 1024x768 so that is what you will want to design your presentation for if you want maximum conversion. Figuring in room for the browser elements, you are left with about 1000x550 for the design.
Think in panels: Not every single graphical block on your tour should be changed with each page. Usually you will take the 1000x550 graphic and cut it into 6 or more pieces of which one or two will be the areas that change as you go through the tour. You may have a cutout of a model, the site name, the join links and other static elements that don't need to change from page one to page two and so on. So when you design this style tour, keep in mind that only one or two panels should contain information that changes page to page and you will have a much faster loading tour overall.
Sequential AND Random: When creating the tour pages think in categories as they match up to the primary categories of your members area. Pictures, live webcams, xxx videos, e-zines, etc... These are all categories you can and should feature in your tour. So, for instance the index page of the tour might be a general sales pitch, page two might be about the photos, page three about the webcams and so on...
Navigating through these pages should be available both in sequential order (via the "next" and "previous" links) and in random order (via a menu type link on the tour with the name of the category that then goes directly to that page of the tour). Offering both means to navigate allows users with different tastes in how they like to access information the ability to be comfortable in your tour and thus conversion will usually increase slightly.
It's all about the samples: The "long form" Type B tour is more about offering samples of your products as opposed to just talking about how great your site is and dazzling surfers with a presentation of graphics. So when putting this tour together you have to carefully select samples of videos and pictures to present. It's generally recommended not to put more than six to eight samples per page.
Organize the samples into individual scenes or by model and offer clear, high resolution picture/screen caps and a link to see a sample video clip on each of these sections (which are also commonly called consoles). One note: not every sample link actually has to lead to a sample. It is common to only have two or three actual samples and the rest of the consoles linking to the join page. Just how many actual samples you offer is a matter of testing. Try a couple, try them all... compare conversions and go with what worked best.
Just enough to tease: Be careful on your sample pages not to give up too much. The point is to get the surfer aroused so much that they just HAVE to see the rest of the clip or more of that model's pictures. If you go too far though, they will "get off" to the sample and be gone. This, of course, is less of a problem than not getting them aroused at all because the surfer who "gets off" might revisit and then join later hoping for more of the same. So if you can't decide how much enough is; it is better to err on the side of generosity.
Personality: Type B tours often do better when you inject some personality into the descriptive text. Don't just drone on about how awesome your site is and how truly great the content is... say something specific about the samples you are offering and what is happening in them. Comment on the action in a video, talking about stuff that is in the full video not just the sample size and use words that you would use when speaking to a friend. People are inundated with commercial sounding pitches and they get numb to them. Be a bit more conversational and you'll see conversions jump a bit.
Page Rotation: With long form tours you can either stack samples so there are a bunch of consoles of them per page or you can do one sample console per page with links to all the others at the bottom. When doing the single sample per page, it often works well to use a simple PHP script to select which sample appears as the index page randomly. This way a returning visitor might get a different sample than was seen last time. It tends to raise conversions.
There you have it. A bunch of elements to consider and put together!
But let's say the tour is up now and you want to increase conversions even more. This is when you start playing the swapping game. What this means is that you will take individual elements of your tour and try alternate ideas for them. Usually you run the alternate ideas in three day blocks and then look at your stats to see the conversion difference. Of course, you keep the idea that gives you the best conversion increase. It's important to do only one swap at a time (so you know what change has had the effect, positive or negative) and it is also important that you do this during a time when you are sending pretty much the same type of traffic to the site without any significant increase or decrease. By way of example of some common "swappables," check out this list:
Join link text: Instant Access, Get Password, Join Now, Full 24/7 Access, etc...
Samples: Try to change which video or picture samples you are using. Eventually when you have a good member base you can view your stats or even poll your members to see which videos and models are most liked and then use them in the samples of your tour. In a Type B tour, the samples you use have the greatest effect on conversion.
Sales text: The wording you use to describe samples or just the list of sales points on a Type A tour such as "24/7 Live Webcams! HOURS of XXX Videos! Etc..." can be tinkered with to see what gets the best response.
Colors: Some sites do better with different background colors or text colors than others. Having a run of three or four color palettes ready to go is another swappable category.
The list goes on, of course and is dependent on the tour. One final note to cover is when to use Flash? Having small Flash elements (or "bricks") can be very effective in increasing conversions so long as you keep the file size small and you don't let it be more than 20% of the page presentation at most. The best use of a Flash brick is in a redundant manner to another area of the site as well so that the few (and they are fewer every day) users who don't have Flash don't miss an entire sales point. If you have a list of site features somewhere it's not going to hurt you to present those same features in a cool Flash brick too.
That covers the discussion on tours. If you follow all this advice and are getting traffic from decent sources you should have no problem reaching at least 1:500 (Unique visitors to the index page) for your conversions. The number can be better for niche sites and low traffic sites and not as good for TGP trafficked sites and sites employing misleading banners to get traffic. Be patient with the swappable elements and the period of time it takes to go through them. It pays off in the long run!