Keeping track of sales during the day makes this easier to manage, and it's also a great way to find out which products sell best! (blog.folksy.com)
I know this is obvious but it must be pointed out that you need to keep track of your sales during your promotional campaigns. (writingbytheseatofmypants.com)
So I kept track of the sales ranking and units sold for six of my ebooks over a 90 - day period in 2012. (writingforaliving.us)