Whether you want to be a hand model or swimwear model, submitting photos that say what you are capable of is best.
And becareful and considerate when submitting.
If you are submitting to an agency ( commerical/ and fashion): submit a face shot without heavy makeup, show some energy in your personality, include a shot that looks like an ad- with a product. Mention a recent modeling job you did, or your interests and what you would be good for.
If you are submitting to a magazine: Submit photos or a compcard that match the style of the magazine, -it is important to send images that flow with the vibe of the magazine. Also submit a short letter with your resume or some credits and your interest -with your contact info. Have an email that involves your name. Such as email@example.com and a phone number
Submitting to a photographer: Submit a recent shot, a close up, a full body shot. And share examples of the type of shoot you are looking for. Submit samples by sharing websites or the name of the magazine or for a headshot-the TV show or film, that has the style of a photo you are looking for so that you can get what you need.
Also when pitching a photographer an idea to get test shots: Mention your experience, none- very high,- and then mention what you are looking for and what you will be providing for the shoot. Can you find a location? help with styling? Do you have an intriguing idea that might interest the photographer?
Submitting to a brand: Research the Headquarters location, and phone number and try to get the email of the right department you need. Such as the marketing department which picks the models usually. Submit photos to the marketing department or pr department, submit a nice headshot like a a close up, a body shot, and a shot that matches the style of the brand. If it is a shoe product, send a photo of yourself wearing shoes. And focused on the shoes and which looks like an ad.
You have self serve, you have to research, submit, and keep trying to market yourself. You have to take risks, try, and not give up!