If you are not happy working for a company or other parties, and planning to run your own business, you should try freelancing. There are many websites on the net you can find that offers freelancing work: You can check Upwork.com, fiverr.com, freelancer.com.
There is also business called property agency. Assuming, they operate standardly in every countries, they do not require a degree to join, AFAIK. Some brands has an international reputation. They operate multinationaly. Marketing consultant is an associate of the principal, a holder of frenchise rights ; not an employee. They are paid based on commission only on successful sales; not salary. Briefly described, their business is to try to find a leasee, for a rented property, or a buyer/investors for a landlord, a property owner (apartment, house, etc). Since You tell us that you rent an apartment , I guessed, You may have meet a property agent who may have introduced you to the apartment owner, making an rental agreement between you and the owner, and also asking you as a tennant to pay for the rental price.
It is the right business for someone who is popular, has many acquaintances, confident dealing with people, and an optimistic one, loves outdoor work, teaching, physical exercise, and loves for freedom from 9-5 working hours. If you are interested in business, this job might be for you to learn and understand investment in property. You may also find yourself teach your client so that they do not make a bad property investment decision.