The great thing about the economy of the modern world is that it is highly diversified. If you were to go back around 150 years, you would notice that people that wanted to start a business could do little more than open a grocery store, a bank, a school or perhaps strike it rich by finding oil out in the middle of the desert or some other valuable commodity that they can sell for a massive profit as long as they are lucky enough to find it in the first place.
These days you have a lot more options that you can go for when you are trying to start a business, and if you know a few models that are willing to work with you then starting a model agency can be pretty fruitful in some way, shape or form at any given point in time. A big part of the reason why that is the case has to do with the fact that there are countless trade shows that happen each and every year, and all of these trade shows will need models that can help sell products and entice people into checking out something new for a change.
In order to start a modeling agency, you first need to get your business registered. Another thing to do would be to find models and have them sign contracts with you, as well as make a few contacts and connections that will enable you to find gigs for your models. Once you find a few gigs, more models will come to you and you can slowly start to expand your business by leaps and bounds in no time.