This breaks down into several bits: PR, advertising, identifying good markets, and building packages to sell into those marketplaces.
PR, based around the "Here's a great system you didn't know about that's a real joy to use and it'll save you tons of money etc" stuff;
Advertising covers publicity stunts, preferably cheap ones, the usual posters and stuff, media activity including writing articles, booking and staffing stalls in odd exhibitions, and helping to run even odder exhibitions.