Advertising and marketing are really the same things to me, while marketing does encompass a bit more of the front end work being done, it all starts with having a good plan. Without a plan, your advertising is shooting in the dark and potentially wasting a lot of time and money not reaching the right potential customers. The first key to good advertising is having a good plan. The plan and corresponding goal can't be "I want more customers". Rather, it should be more like "I want 10 new customers that buy full-color black shirts in quantities less than 12 in the next 3 months." This would be S M A R T Goal which means Specific, Measurable, Achievable, Relevant, Trackable.
Another critical element would be knowing your customer inside and out. Who are the current customers you have that you love working with and can’t wait for them to call again? Who are the customers that you cringe when they call and hope everything goes well? Define your "customer" in detail based on the customers you love to do business with and make sure also understand what quality they should not have based on the cringe-worthy customers. I even go so far as to name them, as you would a new child. What name sticks out to you as the name of the person you want to be your customer? This helps you visualize your message, and puts you in their shoes while you decide how to get in front of them. Then your marketing message can be created with your niche and what your ideal customer needs so you will only have to spend money and time attracting the right business, not attracting anyone and everyone and having to qualify them or turn away customers you don’t want.
The last piece of good advertising is making sure you have set and placed a clear call to action in the message. What specifically would you like your potential customer to do once they see or hear your advertising message? Do you want them to call you, do you want them to buy something, do you want them to get a quote from you, do you want them to come to your store and other actions possible? Finally, once you have that call to action, then you want to try to fit it into your advertising message up to 3 times. Once at the beginning to capture those people that are ready to go right away and want to be first in line. Once again in the middle of the message for those that need a little more details first, and then again at the very end. The CTA at the end of the message is for those potential customers who need all the details and might be on the fence. Give them one last chance to take the action.
With those three pieces, you should be able to spend the least amount of money possible and have the best return on investment for your marketing dollars.