I'll be blunt: you can't.
I've ran design agencies for years and in the beginning I was obsessed with this question, thinking our dashing service could win them over. "If only we could get in the door our problems would be solved!" I'd proclaim to no one in particular.
But over time with hundreds of clients beat the truth into me.
There are three factors in every purchase: speed, cost, and quality. Most buying decisions are based on emphasizing two. Fast food is speed and low cost, missing quality. A fancy steak house is low speed, high quality and cost. Everything is a compromise.
If someone doesn't *value* quality they won't pay for it. If someone doesn't have the *budget* to afford quality they won't pay for it.
So, the bad news: elance is filled with the above.
This is why you're not winning there. Their qualifiers are misaligned. That is not knocking elance, it is just a reality. They don't want a conversation they want a low cost solution. It is insanely unlikely that you will walk away with longterm clients who value what you do and are willing to pay well for it.
But there is a silver lining...
This means you can focus on customers who you can win with. Those that value quality. Those that believe in responding when you put some effort in. Those probably not on elance.
Love to help on the agency end if I can at all in the future too about how to find clients. Feel free to reach out to me through Clarity and you'll be helping a good charity at the same time.