Many models (if not the rest of the world) have heard or seen the term TFP or TFCD ("time for prints" or "time for CD"). Essentially this is a trade between the parties involved, at minimum a photographer and a model, but may also include an MUA (Make Up Artist) or stylist (whether clothing or hair).
In many situtations whether you're just starting out as a model or have an established portfolio (or "book"), it may make sense to ask for TFP/TFCD. Photographers who are starting out need to build their book also, so this is a mutually beneficial activity. However, established photographers may or may not offer TFP or TFCD except in exceptional circumstances defined by the photographer (which may be as simple as, they have time on their hands next week due to a cancellation and your look may benefit their portfolio). Conversely you may want to work with a photographer who has a certain style lacking in your book, so offering TFP/TFCD when you would otherwise charge for modeling isn't unusual or "backtracking".
Note that there's no expectation of quality work with TFP/TFCD, although when you pay a photographer, you should have certain quality guarantees (if at a minimum, a guaranteed reshoot if something doesn't come out right). (And you have to be reasonable about this: if the photos are technically fine, but you didn't like your hair color or shoes that day, these are -not- reasons for a reshoot). I will say this: I know many photographers who are up and coming that are incredible photographers, so going TFP/TFCD is not to say you won't get quality shots. The photographer wants to show off good work too, so it's in their best interest to do well. However, when you pay, you may have more of a guarantee about getting quality work.
There are other expectations you have and benefits you get by paying a photographer. When you pay for photography, you are (or should be) guaranteed by the photographer to get "n" number of prints or "n" number of images on a CD with a license to print, and your expectation should be a pretty quick turn-around.
With TFCD, a photographer is not required to give you a set amount of images, although the expectation is that's what you're trading for. With TFP, you should agree up front how many prints you'll get (whether many, or one you can duplicate from). When you pay for photography you're under no obligation to sign a model release and the photographer will have limited rights as to what they can do with your photos. With TFP/TFCD, the photographer may insist on a release since the benefit to the photographer is being able to use photos from your session. This is not always a deal breaker, but just be aware of this before hand.
With TFCD, make sure you are promised images on a CD are high-resolution, usually 300dpi. For images that are going onto a web site, you need low-resolution images, usually 72 dpi. Good photographers will provide you with a set of each on CD. Expect the low-resolution images to have some branding or watermarking by the photographer which may be as simple as a small copyright on the lower side, or may be a more complex logo of the photographer or studio. Prints may or may not have a copyright or logo watermarking on the front, but will almost always have a stamp on the back.
Either way, when you get images on CD, make sure you get a license or release to make prints from the photographer. If you need to make extra prints from your portfolio shoot, most print shops or copy shops will not duplicate an image with a copyright notice on it, or even one that looks like it's professionally made without having a signed print release from the photographer.
Great resources for models looking for local photographers willing to offer TFP/TFCD are www.modelmayhem.com and www.bemodel.com.
There are more issues here to discuss for another entry, specific tips and secrets about model releases. Stay tuned.