I did this for 8 years. First of all, get yourself known. Unfortunately, this will mean working for a company full time until they (and others) get to know you, unless you already have this cracked.
Freelancers get hired if they turn up on time, don't crash, do the job with no fuss, are smart and tidy and don't try to take passengers away by handing out their own business cards.
Think of what a Chief Pilot needs (i.e not to be dropped in the sh*t) and start from there. What machines do you have on the licence?
Phil