My experience has taught me that for the most part, you are your best advert.
Turn up on time, well turned out, shaved, [or with a tidy beard], not stinking of tobacco/drink, and with clean clothes.
Do a good job, at a decent price, and you will get recommended.
[The ladies amongst you may ignore the bit about shaved - I think!]
I believe it was Ralph Waldo Emerson who said something along the lines of,
"Build a better mousetrap/ preach a better sermon/ write a better book and the world will beat a path to your door."
Baldeagle