Every business has seasonal swings. Take a look at the natural rhythms of your business. Determine what percentage of sales you'll be able to devote to marketing. You may want to call the trade Association for your industry to ascertain the standard for your field. Take into consideration your market and competition.
Consistency is key.
You want consumers to think of your business first when they're in the market for the products or services you offer. Think of an ad that grabbed your attention. If you think about it, the ad that caught your attention probably spoke directly to a need or desire that you have. Too often, businesses advertise their products and services with little thought as to why people would be interested in purchasing their particular product or service. They highlight the features of a product or service, but not the benefits it will deliver to the consumer.