If you are from US or UK you can try textbroker, they have a variety of projects available. Else, you can opt for iwriter, odesk or other freelancing sites to get a move on. You may not be paid too high at the beginning but that can gradually increase with time, if you maintain good quality. Forums like DP, WF or BHW are also good spots for selling your writing services. All you need is few good samples up for exhibition here.