I don't think you are gonna do any good with a membership type site. Actually it's phyisically impossible.
Let's do some math.
Let's say 1 memebrship cost 30$ a month for example. And that u will have 10 girls online all the times.
Let's say a professional camgirl earns 100$ a day for 8 hours work (that's her share, or the tudio sharere, not yours). Some make less some much more but let's say on average.
So for 24hrs you need to make 300$ to "pay" every girl, just to pay the girls... nothing for you

and to have $300 a day you need to have 300 members... You know what means for 3girls(3shifts in one day) to make 300 memebers happy??? Impossible.
THis would guarantee ONE 24/7 live show. Imagine if you want 10 girls online all time...
And that is just to cover the girls expenses... Still nothing for you and nothing to pay for server, webmasters, promo and all the rest.
Ifriends or Imlive fanclubs are a plus to the payperminute... members have some feature like can see the email of the girl or some free videos or exclusive pics but can't be the main income.
The only good thing is that they are recurring ...funny I have one girl not performing for more than one year and still having 3 ifriends members on her fanclub paying every month for nothing.
So what can I suggest...
There are 2 types of sites that in my openion can be successfull:
- Pay to View = u see nothing unless you pay (ex: camcontacts or imlive or tricams)
- Pay to Private= u can free video chat with the girl but pay for a private show(cumtv, livejasmin, flirt4free)
They both have pros and cons.
Pay to Private is maybe easier to attract traffic but you can endup with a bunch of free loaders and a big server bill at the end of the month. (you will need to rebroadcast the performer video from your server)
Pay to View is chaper to run (you can have a performer/viewer peer2peer solution) and it doesn't waste the performer too much time so they can stick your software in the background while working on other sites. Only problem is that is quite hard to attract customers as they see nothing but a few pictures before they pull they credit card out.
The ideal solution would be what "streamate, aka vipstream(wegcash) or epiccams (********) is using.
Ie: Pay2Pvt but you need to provide your cc to see the free shows even if not get charged. That will ensure all the viewers with no credit card to stay out of the game but then again it's not easy for people to give your credit card details if they see nothing before.
There is an already made system that is doing quite well: check it out at
http://www.firecrackervideo.com and you can see the a demo of it at
http://www.livejasmin.com
It can handle a lot of viewers and performers on the same time of course depending from the server performance and band.
Another good choice would be a flash communication mx solution but you still need a developer to adapt it to your needs.
After you chose you system you need to worry about performers and traffic. I would worry about traffic first, infact normally girls and studios try new sistes, at least for 2,3 days or 1 week, maybe they put you on background while working somewhere else, but normally they test you. If nothing happen in terms of money for them in 1 week they leave you and you are done. The voice will spread and you will be classified like a crap site.
If in that week they make money in less than one month you will have your site full of performers 24/7. Studios and performers are like a big family they spread news about new sites very fast.
I could keep on for hours so if you need to know something more specific just ask.