1. Passion.  This probably goes without saying, but if you don’t like taking photos or using photoshop, then well, you might as well just stop reading now But if you do love photography and/or photoshop then learn all you can about stock photography. Look through magazines and web sites at stock photos and find what type of stock strikes you as interesting, and do it. Is it lifestyle, adventure, sports, isolated objects, food? Basically, pick what you like to (or would like to) take photos of, and find out what sells in that category.
2. Photography Skills. You may be surprised to hear this, but you don’t have to be a great photographer to create good stock imagery. I have many photos that have made several hundred dollars each that anyone would consider very average photos. Their concept has made them sell, period. Of course it always helps to be good at lighting, composition, and such. But you don’t have to be ‘great’ at them to be successful, just better than average.
3. Photoshop, Photoshop, Photoshop. Developing your photoshop (or other good editing program) skills is really essential to becoming a good stock image creator. This is how you turn good photos into great photos. You will often want that model or object to not just look good, but look really good, and with Photoshop you can make it happen. This is also what will help you move a 50% acceptance rate up to 90%+. Too much grain here? Blur it out or downsize. Purple fringing there? Remove it. Hopefully I’m not making it sound that simple, but if you develop your Photoshop skills, after a while it will become that simple.
4. Time. You do need some extra time, but if you have the Passion and drive to make this happen, you will find the time. Personally I worked 15 straight months on stock photos logging about 3 hours a night, 3-4 nights a week, and holding 1-2 stock photoshoots a month. And at the end of those 15 months I was bringing in over $4k a month. You may say that you don’t have that kind of time or desire for another part-time job, and well, you’d be right. But for me, it wasn’t a job, it was a hobby that was addictive and made a good passive income. And what’s better than a hobby that makes money?
5. Resilience. You will have photos rejected, and rejected again, and rejected again. If you haven’t already, you will have to learn to learn from those rejections, improve, and keep shooting, processing, and submitting. This is no get-rich-quick scheme, it will take many months for the hobbyist to see much progress. If someone tells you that you can replace your current income in a month then well, I’ve got a great investment opportunity for you too. All you have to do is wire some money to my bank account in Nigeria…

Believe it or not, that’s all you really need. There is a lot more that will help you be successful in stock photography: your ability to work with people, your creativity, etc… But the above list really is I think, your basic tool set. Remember, most people who try microstock give up. They do not have the passion, resilience, or desire to stick with it and they end up with nothing. Those that do not give up however, end up with a nice $100, $500, $1000 extra cash a month and an extremely fun hobby. Unless you become better than just ‘above-average,’ and then in four years we’ll be calling you the next Sean Locke or Lise Gagne