I joined in October, 2012, uploaded 53 photos in November and had my first sale on December 9, 2012. As of January, 2015 I had 1,000 for sale with 90 sales. My suggestion is that you shoot anything trendy. I get an e-mail each morning from Yahoo which anyone with a Yahoo email address gets automatically. At the bottom, it lists the ten most popular searches for the prior day. For example this mornings searches were for E-file tax return, IPhone 6 Plus, Medicare Part D, etc. It gives me ideas on what I should be shooting. I would suggest you take a photo of an elderly person taking a Selfie. Things like that. Also, I've had four sales so far this month, 2 via Alamy (now at 1740 photos) and 2 via Stockimo (377 photos). So you might be better off going the Stockimo route, which has a modern vibe. I don't think you should give up, just try a new, more current subject matter to see if that sells. Best of luck to you.
Very good advice for us all, Lisa. Thank you.