For starters, it's important to decide how large your operation will be. The size and scale of your operation can be very dependent on the type of sublimation you're planning to have done and the amount of capital you have to fund it. If you plan on doing the design and printing services yourself, you will only need to worry about buying a machine and the supplies necessary to run it.
However, suppose you plan on managing a larger size operation where you will employ designers and printers. In that case, you will need to worry about building computers, purchasing software, and providing equipment that can handle the workload.