First, you have to know the franchise rules of your country. Each one has a different regulation.
In any case, you have to understand if your company is "franchise", that is if you have all the requirements to be able to sell your brand franchises, and you must: format your company so that it can sell franchises and succeed.
Some important points; How many subsidiaries do you have in the market? Are all of your processes documented? Can you give support to anyone who buys your franchise? What people do you want to have as your franchisees?
These are some questions and I think some articles I've written can help you get a better look at this fascinating marketplace.