I think that wherever you post your work/services, you might need to initially build a pretty large user base or following. That might be the first step, since an unknown or new user might just get looked over, or lost in the large amount of activity. Some people mentioned Fiverr and it is a good option since it is a competitive area, and people can find you easily, instead of the other way around.
To many competition are in that platform with high quality experience and feedbacks to their clients so before you can compete then for sure you need take a lot of effort just to get a client. Maybe from there you can start but expect to take a lot of effort on promoting your works and also yourself since once you get a client and you do a good job for sure those clients will hire you again and refer you to their friends.