I'll leave you to judge the ethics of this idea (a few friends actually did it and got the best pics of her life):

1. Take the photos you have, or some cheezy snapshots. Make a free "model's" account OneModelPlace.com or one of those similar "portfolio" places. This is usually free.
   
2. PRETEND (if you are just after good pics) TO BE SERIOUSLY INTERESTED IN MODELING!!! Anyone posing infront of a camera is as much a "model" as the person with a camera is a "photographer".
   
3. Very Important: TFP means "Trade for Portfolio"- where so-called photographer and so-called model get together and shoot with the goal of creating portfolio quality images. You should receive a cd of images or quickly emailed "touched up" images. TFCD is "time for CD"...
   
4. Browse photographer portfolios and show "desire to work with" and inquire if they would be interested in doing a TFP shoot... Read emails from interested so-called photographers who are interested in so-called shooting with you. Follow safety tips below this list and use your best judgement in working with them.
   
5. Go on "TFP shoots" until you have the great photos of yourself that you really want. BE SAFE. I've included some safety tips below.
   
6. Remove your "portfolio" if you're no longer interested in so-called modeling.

Now, Safety is MOST important, because these guys may or may not be on the up and up, and you wouldn't be doing this if you could afford to shell out bucks for Glamour Shots, Olan Mills, or one of those types of BUSINESSES. Photographers are individuals, and there's a portion of poseurs, cons, and talented-but-messed-up ones who are creepy at the least, and rapists/murders at the most (read my blog on "scammers"- there are a zillion more of them, even fairly talented ones, who aren't worth the trouble of anyone working with).

Here are some Modeling Safety Guidelines that I've learned:

1. Take someone with you, or meet in public to discuss the shoot first. Coffee shops are good places to meet. Sometimes it's not possible or comfortable to take along a friend, in that case, you need to be really careful.
2. Ask for details (either on the phone or meeting at a coffee shop beforehand). If the guy is an amateur with good pics in his online portfolio, what is his day job? What are his goals? What are his favorite things to photograph? Why is he interested in photography? What is his idea for a shoot with you? If you only ask one question, ask him how he feels about you bringing along someone and answering your cell phone during the shoot (ask this even if you plan on not bringing a friend, his answer will tell you alot). I've never shot with anyone who had a problem with me bringing along a friend- I don't reccommend you do either.
   
3. Make him aware that a few friends know about the shoot, have his number and information, and will call if they don't hear from you. This is especially important if you are shooting alone.
   
4. Give his information and shoot information to atleast one friend.
   
5. Call a friend and answer your phone during the first shoot, assuming that you're shooting alone.
6. About the "model release", if there is one: Assuming that you didn't get undressed, pose in lingerie or swimwear, it's probably the courteous thing to go ahead and sign it. You might end up as stock photography, though. Some photographers make up TFP "contracts" which just clarify that neither party will profit from the images without the other one's permission. With No Contract, images are legally for portfolio and personal use only.
7. Use your intuition and go by your gut feeling! If something doesn't "seem right" or "click", don't give the guy a second chance. There are too many nice so-called photographers out there who will not give you bad gut feelings to settle for the possible criminal who doesn't "click".
8. Consider finding a photographer thru a non-modeling site such as pbase. My experiences with those who are primarily interested in taking photos of non-people have been consistently good. However, they might actually be full-time professional photographers who make money off their images and want to charge you since they usually don't take pictures of people :-)
   

Note on "glamour", lingerie, and nude modeling: If you're wanting some good photos of these kinds, I reccommend saving up and paying a studio operating as a business. If it's your boyfriend's Christmas/Birthday present and you are totally broke, then here are some more safety tips and info, from my own lessons learned:

1. Do not sign away the rights to use your images for any type of "sexy" shoot. This is usually in the form of a "model release". If they want the rights to resell, alter, and commercially benefit from your partially-dressed-to-nude images, make them pay you. In NYC the going rate for nudes is around $100 an hour, in Buffalo it's around $50-$75 an hour, and in Springfield Missouri it's $80-100 an hour (the economy is better in Springfield than Buffalo and fewer girls will get naked out there).
2. Be aware that consequences of signing the typical "model release" and relenquishing rights to your images include: ending up on a porn site (as teaser material even if you aren't nude), ending up on sites advertising prostitution and escort services (I know a fashion model this happened to), your pictures portraying a phone sex gal... and any number of ADULT Related Products, Services, and Web-Content.
   
3. If the photographer starts pressuring you to do more than your limits, which hopefully you've made very clear beforehand, then LEAVE. If your limits were "no spread leg", then the so-called photographer should respect that without questions.
4. I would reccommend asking these kinds of questions before the shoot (in addition to their feelings on you bringing a chaperone): Do they use an SLR camera with a flash and backdrop/professional lighting set up (if they DON'T, then you don't want to work with them- too many guys with good equippment doing TFP- read below).
   

... and hopefully you have a great experience and come out with some awesome pictures from all of this! If you decide to be seriously interested in modeling- print out your best pictures and send them to actual legit modeling agencies in states that regulate it (New York, Florida, and California). Beware of potential scammers, and that any person from one of those states who calls themselves an "agent" has to be liscenced. If they're NOT in those three states, well- I could live in Missouri and call myself a "model agent" :-)

Furthermore, please note, that professional photographers are as often creepy as amateur photographers. I think that guys with cameras/amateurs are often as pleasant (and sometimes preferable) to work with; and if they have the money to be spending on good equippment, chances are that they have good employment and don't want to end up in the news as the Morning Rapist, or ruin their professional reputation.

This is all I can think of to write at the moment, but I know there's a ton more that I've learned!