Executive Search Firms
In order for an employment or executive search firm to be interested in investing their time marketing you, you have to sell them on your background just as you would when directly approaching the potential employer.
State your case for why you could benefit the type of firm you want to be hired by. In order to do this, you must know who is probably looking for you. Research potential employers and gear yourself to their needs!
You must first convince them that you have the right skills for the job. There is no greater technique for getting referred to potential employers than that of researching the industry and occupational areas you are in. Use library and published resources first!