Appreciate this is now a fairly old thread but just wanted to add my tuppence worth......
dash t the biggest piece of advise would be to follow up......dont simply contact an agent or which ever client you approach by sending leaflets or whatever and expect them to contact you, these guys have loads of contractors over time contacting them but you will have to do be different in terms of service, price or something else that is relevant to open the door and start to prise any work from a current and no doubt established contractor already on there books.
Whenever possible, ask to meet face to face making yourself known is far better than reading your literature alone.
And, dont rely on one or two ways to market yourselves.....measure what works, if it dont work, stop using it!
Terry