freelancer are ruling the domain, because they had early days of advantage, i think all the freelancers should dump that moronic sites and move on to something betters. odesk or elance or some other.
be consistent in bids (don't bid ridiculously low or ridiculously high on project of some efforts).
give your employer a bit of detail about your implementation methods and road map, even thou they will not understand anything they will get good impression of you.
start off with few free or low priced projects to get a good rating in freelancing websites.
investor are mostly interested if the idea is working, so i would suggest you start implementing the idea as your in flow your will get more idea about resources you will be needing to implement and running it. which will help you put together a better proposal to the investor and your will get a better prospective whether or not the idea will work.