Modelling agencies have different niches that suit different models. For example, some agencies represent runway models, plus-sized models and commercial models. Consider the niche you think suits you best and approach reputable modelling agencies in this space to discuss your suitability with their representatives. Experienced agents can assess your portfolio and appearance. If they agree to represent you, they arrange a more professional portfolio. While the portfolio may cost money, registering with reputable agencies is generally free. Agencies take a cut of your earnings when you secure contracts.