I listed foreclosures for a while, but the lender eventually imploded, the assets were eventually bought by an investment group and at that point, things changed enough I decided to get out. It was so time consuming, too, that it was starting to effect my ability to maintain my sphere of regular business and I did not want that to happen.
Getting into the foreclosure listing game at this point is, while not impossible, practically so. Everybody and their brother wants to list foreclosures because once you are in with a bank, you are essentially handed the business, which sounds great.
The down side is, depending on the lender, you may have to carry certain expenses on the assets, such as utilities, maintenance items, rekeying, etc. When I first started doing bank listings, I would typically be "out" approximately $15,000 at any given time (and that was a relatively low amount); I was always reimbursed, but you have to have the cash flow to be able to do it. Another REO listing agent in a different office works for several banks and always keeps a $100,000 equity line open to handle her expenses. Now, not every bank requires this, many have asset management companies now that carry the expenses, but just be aware it is a possibility.
Listing REOs is extremely time consuming, if you do what you are supposed to do. There are endless issues with these properties, including maintenance (every time there was a heavy rain, another agent and I were hauling out the portable generator and a wet vac so that we could go pump water out of basements we knew were going to flood - this is just ONE example of the kinds of things we were always doing), break ins, broken windows, vandalism, rental scams (yes, people advertise foreclosures on Craigslist and then rent them out to the unsuspecting who are desperate enough to find a cheap rental and don't ask enough questions), broken pipes, etc. etc.
But enough about the pros and cons of foreclosures; these days, there are thousands upon thousands of agents who have a great deal of experience in managing bank assets. Trying to break in without any experience in the field is almost impossible, so my suggestion would be to seek out a REO team or REO agent in your office and see if they can use your help in exchange for gaining some of that experience. There is a lot of paperwork to stay on top of, so you have to be extremely well organized to survive it all.
It's not for everyone and requires a definite skill set.
As for selling foreclosures, I would do that every day of the world, however, the most critical aspect of that, to me, is knowing how to best counsel your buyers. Be sure they know what they are getting into and what protections they are yielding to the bank. Other than that, though, they are pretty sweet.