If you’re an agency represented model they will help you, but if you are going the freelance model route then you will need to build a portfolio, which will also help you build your network and will help you in getting paid gigs.
First thing to know when seeking to build your portfolio is what type of modeling you are considering doing. If you are pursuing fashion, it makes no sense to seek out a senior picture photographer. Once you have some ideas the rest is easy.
Now there are 2 ways to get pictures for a portfolio, both with pros and cons, which I cover more in depth in my post “TFP/CD vs Paying“, but basically it boils down to how soon do you want them and how much time you have to invest in them. Paying a photographer, while expensive, means you’re getting the exact look/style you want. TFP/CD might mean more shoots, with various photographers, to get what you want, but you have to invest time not money.
The final decision is what sort of portfolio you’re going to maintain, you can have a physical print book(s), an online portfolio or a mixture of both. A physical book is good for casting calls, go-see’s and such, while an online portfolio will allow you to network through social sites and online castings. So for most the answer is a mixture of both, so they can blanket out for many different jobs. The final decision is your choice and based upon what your market needs are.
This image by Conceptually Black of a model smoking is not great for a portfolio, but is an indication of concept a model could do with a photographer, so both parties receive something for their respective portfolios.
The following headshot was done at the same shoot, so the model got something of value from the shoot as well.