At first, I though It was mainly "Search" by keywords. However, Things are not so straightforward after I got a chance to look at my sales today, though my portfolio is very tiny which definitely is not significant from statistic point of view.
On the sales report page, there is a column called "Buyer searched after", so you know how buyers found the photo, either search-by-keywords or "n/a". I only have 5 sales at this point, but only one is search-by-keywords, 4 are "n/a", which means buyers found my photos by other ways 4 out of 5.
From what I see, buyers could find photos by reading blogs, message boards, collections, or from links on other photographers, and other ways I don't know at this point. For newbies like me, it's probably very helpful to advertise your portfolio by writing some blogs, messages on message boards, etc., otherwise our tiny portfolio probably will be lost in millions of good photos. Certainly the quality of your photos are the most important.
So, How's your sales reports look like? by "searching after keywords" or "n/a"?
I hope this info is useful for newbies like me, and finally thanks for reading my blog, and enjoy the fried noodle I made specially for you: