CMU's "bomb lab" is pretty famous for providing an executable to play with. Actually I think all the assignments that go along with the CS:APP2e text look very valuable, http://csapp.cs.cmu.edu/2e/labs.html
It's just one of those areas you have to get some hands-on practice doing.
There is a great free text, the author asks for a donation: Reverse Engineering for Beginners, http://beginners.re/
The RCE Endeavors blog has many great posts that aren't difficult to follow, http://www.codereversing.com/
CMU's "bomb lab" is pretty famous for providing an executable to play with. Actually I think all the assignments that go along with the CS:APP2e text look very valuable, http://csapp.cs.cmu.edu/2e/labs.html
It's just one of those areas you have to get some hands-on practice doing.