The main message of microstock sites is: “Why would you let your photos pick the dust on your harddisk? Put them out for sale and earn money.” When that would be the main reason for an amateur photographer to engage in microstock photography, disappointment will not be far away. Yes, you can earn some money with microstock. But the average wages per hour are extremely low and it takes ages to build a reasonable portfolio (and by reasonable I mean over 1000 pictures). And effort. An amateur photographer likes taking good photographs and expressing his/hers creativity in the images. Engaging in microstock means, however, extra work. Keywording the work is essential and especially in the beginning time consuming. Then you have to go through all kinds of review processes to get accepted by the stock agencies. And of course, upload the work can also take some time.
So my conclusion is: let money not drive the engagement with microstock (at least not in short or medium turn). But why then would one want to engage? Speaking for myself, with only three months experience with microstock, there is one reason that I really find appealing: the whole process of submitting images to microstock has raised the quality of my photowork. I think I had quite a bunch of nice images, but many did not turn to be good enough for microstock. Artifacts, wrong sharpening, this kind of things that you often don’t even see in first instance. The main trick of microstock reviewers, however, seems to be looking to your images with a 100% crop. That reveals artifacts..... But microstock also initiates a learning curve. Because I had kept all my original images as RAW-files, a simple review fo my library did the trick of upgrading the quality where needed.
So now I am building up a portfolio, now almost adding up to 200 pictures. Not much, but you have to start somewhere. I really enjoy my images being sold, and am constantly wondering how on earth they can be found within the huge digital mountain of millions of high quality photos (-:).