The more know-how you have about the overall marketing process, the more profits you will earn. Great marketing involves both insight into marketing know how and intuition into what tools are likely to succeed in a given situation. Both are needed.
With insight and marketing know-how, you may not be able to create great marketing, but you will be able to know the difference between great and gruesome marketing. Knowing the difference, with dealing with freelancers, advertising and the media will have a potent impact on your profit and loss statement.
Guerrillas know that most of their competitors don't take the time to learn. In an area with 100 businesses invited to a marketing seminar, fewer than 25 are likely to attend. Be one of those that attends, however, and you'll gain a significant advantage.
Besides books like the Guerrilla Marketing series, subscribe to publications like Ad Age, Ad Week, and know how to adapt distant successes to your area. And when in doubt, submit questions to the Guerrilla Marketing Association forum!