To increase income, a written Marketing Plan is essential. It doesn't have to be long, fancy, or public, but it should exist to help the owner resist distraction, stay focused, and remedy the "feast-or-famine" tendency that results without one.
A good Marketing Plan consists of the following basic elements:
Goal: a dollar amount, usually annual income. "More than last year" isn't good enough. It must be a number. The best way to develop an income goal is by writing a Budget that supports the Lifetime Savings Plan. For a business, it's also a good idea to do a Cost-Volume-Profit (CVP) and Break-Even Analysis to develop a gross income goal that allows for business expenses.
Strategy: simple multiplication, units x average price. If a line of products and/or services is involved, break it down, bearing in mind Pareto Optimality.
Target Market: a description of the characteristics or traits of customers who would benefit from the product(s) and/or service(s) being offered.
Channels: appropriate avenues to use to approach the Target Market.
Tactics: specific tools and techniques to use in the Channels on the Target Market to execute the Strategy.
In general, the tendency is to skip defining a Goal or a Target Market and become preoccupied with Channels and Tactics like advertising, events, mailings, hardware, software, web sites, search engine optimization, the latest in Social Networking, etc.
Those are all great things, but they're mere tactics. What makes them meaningful and useful is to put them in the context of a Goal, and a Strategy for attaining that Goal. Once that's done, then questions of scale and optimality become answerable.
This is Seth Godin, marketing expert and originator of "permission marketing", "America's Greatest Marketer" and former Marketing Director of Yahoo.com. (Notice that his background is in Philosophy.)