You basically should invest some time in building up a portfolio of your own projects.
Otherwise you basically have to either undercut everybody in your bids to make yourself attractive on a cost basis, or when you bid on a project, show the customer a "proof of concept" or something that shows you already have something solid to show them before they choose a freelancer, which may or may not be feasible for the type of projects you're interested in doing.
Have a couple of projects that you've created that you're really passionate about. Be able to explain why you made the design and programming choices you've made and be able to honestly explain them with enthusiasm.
That's really the best advice you're going to get.
Otherwise you basically have to either undercut everybody in your bids to make yourself attractive on a cost basis, or when you bid on a project, show the customer a "proof of concept" or something that shows you already have something solid to show them before they choose a freelancer, which may or may not be feasible for the type of projects you're interested in doing.