That's a really good question. The problem is MANY freelancers give other freelancers a bad name by being unfocused, uncommitted, and hard to work with.

I think a good way of showing that's not you is kicking off your job interview process by submitting something with your intro email and resume that is germane to the company/team you're interested in joining. Perhaps a coding project, a UX design, a marketing plan -- something that shows you care.

That'll make you stand out not only among freelancers, but just about any applicant.