Hi

As Neitsa already pointed out, the best thing to learn is to try something on your own. I think what he forget to say is that you should start with more or less easy targets. It doesn't make much sense trying to reverse an ASPR protected app as a beginner.

Have a look on some shareware sites and check out some new software for serial protections and something. On this way you can see many different serial algos and how to reverse them.

If you think you are ready for some real stuff, check out a Safedisc 2 or Safedisc 3 protected game. Try to look for their softice checks and bypass them. Later in Safedisc reversing you will see code which decrypts itself in realtime, API wrappers and so on. You can find most of the stuff from Safedisc in an EXE cryper, but I always have the feeling that SD2 is easier to reverse, because they don't use as much crap code as the other protectors, so will mostly get a good look into the code.

But before you even start, check out the PE file format. Learn it, learn it, learn it. Also learn to use the Windows API for your own advantage. You can do nearly everything with the standard APIs.

I hope I could give you some advices how you can get started and learn how developers protect their products.

Greetings
Mav