It's best to start searching via Google for local warehouses prior to kick starting your business. You want to know all of the rental warehouses available in your market, what requirements they have to build a business relationship with them, and what the general pricing is for their furnishings/decor - per room. You'll also want to review their contracts and policies to have a better understanding of how deliveries and pick-ups work. Some charge on a monthly basis, but some can accommodate daily or weekly rentals. Knowing their policies will allow you to implement similar policies within your contracts, so they go hand in hand. Some warehouses also offer discount programs. Particularly student discounts if you are in school.
Renting furniture has some clear advantages. You don't need to have a huge investment up front and you don't need to store the furniture or transport it to the home. That convenience allows you to focus your time where its best spent – staging the home. But rental furniture can be limiting, and a lot of home staging professionals find rental furniture to be unattractive. It tends to be neutral, often blandly contemporary, and it can be hard to find a perfect piece for the striking look you envision. Another disadvantage is that most rental companies require a three-month minimum. Most listings, depending on the market, may sell well before 3 months. In the long run, you'll pay more for each piece of furniture than you would buying it.
If you choose to rent instead of owning your own furniture/decor collection, you’ll find that rentals are only a necessary part of your role if you work with mostly vacant listings or new builds. If a home is for sale but already occupied, you may be able to get around by using a lot of what the current homeowner already has - unless most of the furnishings are in rough shape. Of course, rentals aren’t an option if you are staging for a client who owns the home and plans to live there and wants a new touch to their space. In this scenario, you’ll buy specific pieces for the house, within your client’s budget.