I think if you want a way of "just selling" your work to pay for equipment, then the honest answer is "don't do it".
If you wan to sell your work it requires a fair bit of effort on your side, no matter whichever way you go.
Just for the record, I was thinking along your lines once and had a look at Microstock... I think Dreamstime went to 11 odd Dollars or so in several years... - I gave up on trying and just continue to shoot what I want to shoot.
First of all you need to decide which avenue you take:
1) Stock photos:
These are photos that news outlets buy rights to use or that companies buy rights to use for or even buy all rights for a specific image. If you want to go into the Stock Photography business, you need photos that have a publishing potential for advertisements or news stories. One example would be public buildings (city/town hall) or generic images of say writing instruments, a "happy couple on a beach" etc. These images also may not contain any trademarks. You will need a model release form for any recognizable people in these images. (Except for editorial, i.e. news usage.)
Please read about the details if you want to go down that route on the site you register with.
Just some examples of agencies are Getty (top), Dreamstime, Fotolia and the aforementioned Shutterstock.
2) Fine Art Photography:
These are photos that are printed on canvas, paper mounted in frames or under acrylic to decorate homes, offices etc. For that you need images that are worth printing and that would decorate a place nicely. I.e. you need an image that people would want on their wall.
Please consult a lawyer or appropriate sources on trademarks and people in these images.
Such images can be offered via Web Services such as Artflakes or Photoshelter or 500px or alternatively via privately owned websites if you are able to provide high quality prints. (Fotomoto is an option if you cannot print yourself for example.)
3) "Contracted Photography"
I don't think this is suitable for you, but any sort of assignment would fall under this. From weddings, to interiors.
In any case, but especially in cases 2 and 3 you need to ask yourself one question: What will make people buy my photos? And if you are just shooting for fun, I fear it might not be good enough, yet I may be wrong (I have seen some very good images that people shoot for fun and that I think should be printed when they are not, while I have also seen images from photographers who made a lot of money where I do not understand why anybody would pay that amount of money for it - and I have not seen a lot.). Hence, marketing is key here, and marketing takes time and effort.
I have photos on Artflakes, I have some on 500px - sales: zero. Maybe I'm not good enough, but the other truth is: I don't know how to market images to a specific customer base, also I don't really specialize either. (Some people do for example predominantly aircraft shots, others shoot predominantly cityscapes, etc.)
For option 1 just having good photos can be enough, however unless you can get a lot of photos online that people are interested in, I don't see you making any significant income from it. But again I may be wrong.
I hope I haven't discouraged you from trying with my slightly negative attitude, but just having good photos or just being great at marketing is not enough, you need the right combination of both.
Still, whatever you do, best of luck!