A model release form is a legally binding agreement between a photographer and a model, whose purpose is to outline rights and protections for both parties. The model must be at least 18 years of age to sign any agreement--otherwise, consider using a minor model release, which will require the signature of a parent or guardian.
Whether or not you anticipate any future commercial use for the photographs in question, it is best to err on the side of caution and obtain a signed release before the photoshoot. This will shield you from future liabilities and possible lawsuits. Do yourself a favor and obtain a signed release for every session. The extra effort is worth the peace of mind.
Typical benefits of a signed model release includes confering exclusive rights to the photographer, to publish images on a website, blog, advertisement or other marketing materials. You might also consider adding clauses that give you permission to sell, license or transfer rights to another party.
In addition to the considerations outlined above, you may also want to add specific language that is tailored to your particular use cases. For example, it may benefit you to include provisions that allow for digital manipulation (retouching, editing, Photoshopping) or to be clear about using sensitive images (boudoir, as an example) for marketing purposes.
Also, if you intend to offer some sort of compensation to your model, it is best to have it documented in your contract. Include language that specifies any payment or products (often, prints or digital files) that are to be offered in exchange for the assignment of any rights.
The forms and contract templates made available on this website are a starting point and are offered for demonstration purposes only, and are not legal advice. When considering using any legal document, be sure to consult a practicing attorney to ensure the documents you use include the necessary language and that they comply with all laws in your area.