I have heard a lot of bad thing about SOME (not all) modelling agencies and how they make you pay for photos and photo sessions before they take you on then never give you any work. Always check with the local Better Business Bureau in teh US or Trading Standards in the Uk or Similar organisation elsewhere.
I think a better starting place before you go to agencies is if you have a friend who is reasonable with a camera (do not have to be a professional or even that good just okay) Just take 100 photos of yourself in different poses, clothing and backgrounds then pick out 10-20 nice photos. You can then use this as a portfolio, and even better instead of printing them which cost you money every time, host them on a website and get some business cards print with the website address on and just hand these out instead. This is a far cheaper way of doing it and with no RISK. You should never have to pay to get a job if you do there is a high chance it is a scam.
However if you would like a personal portfolio site please contact me and I will set you on up for free. I can design you a fully personalised flash website with as much or little information and then host it for you. This site can contain a gallery of your photos, personal information, list of work, contact details, etc or if you prefer just a couple of photos and nothing else. It can be password protected and all images will be protected as is humanly possible, or the photos can be available to download.
Examples of work can be provided on request. Just message me here if you want, I am a professional website designer but have lots of free time (and enough money) so I am currently doing free sites for small bands, small artist etc, basically anyone who could not afford them otherwise. I have my own hosting server so can offer hosting servers or you can host the site yourselves. No images sent to me will be used for anything other than your site and I will not give anyone your detail or link to the site. You will have complete control and the site can be removed or changed at any time. This is not a scam and I will design a site for FREE, I do not need the money, and enjoy working. If you do want it message me you can tell me what you want and how you want it done and I will help.