Small business owners need to be realistic about their advertising campaigns. Typically, of course, they'll be looking for effective, low-cost solutions, but typically, too, you can have just one or the other; you're unlikely to find a simultaneously effective and inexpensive channel for your ads.
That's why you absolutely must budget for advertising, not just play with the money you have left over. By assigning the right amount of money to the right channels, you can get the results you want, or at the least, improve the results you have, based on the data you gather along the way. Since your monthly spend will be consistent, you'll be better able to measure overall efficacy, too.
Given your need to optimize your advertising efforts, then, here are the best advertising strategies for small businesses.