You know already that you must promote sales and reduce cost. However, it isn't that simple. Hmm. If it is a small business, I recommend using some sort of management software or simply Excel statistics. For example, any statistics related to your sales and cost might guide you to maximize the sales and minimize the cost. Let say you are selling beach volley ball (very obvious example) and you keep all the record of sales in a year. You found that the sales reduced during the winter season (duh..), and you realize that it is repetitive as a yearly cycle. Knowing that this happens, you know, at least, that you got to do something. Just like this simple example, you can get much from refining randomly collected data. I suggest you start off with widely available and simple-to-use Excel software, and if you need more sophisticated and professional functions, you can go for ERP software such as Quickbook, Ecount ERP, NetSuite. I suggest you go to each website and check and compare the functions and price as ERP price can also be your cost, reducing the profit.