Design Crowd Competitions
I have enjoyed using this site as it allows the chance for up-and-coming graphic designers to earn money and build a portfolio as it is paid client work.
The site put designers up against each other to design one item for a client to (there is a range to select from in their list) and then the client will choose the winner and award the designer with the ‘prize money.
You would need to create a small portfolio on the site as well, as there is a chance you could have requests outside of the competition or reoccurring customers as well. The competition description would include details about what the customer is looking for and hopefully some reference photos. You could get a ‘guaranteed’ competition as well, which would mean you get paid a participant reward just for submitting (this generally is a small sum compared to the prize but means you have more of a motivation or incentive to do well on the design.