Please suggest some tutorial / cheatsheet for learning pointcut expressions.
The AspectJ Developer's Guide contains many examples, it looks simple.
AspectJ in Action is also a great source of information about AOP and AspectJ.
Spring.Net has excellent documentation that can be downloaded here: http://www.springframework.net/documentation.html
It has a very good general introduction to AOP and examples and examples of AOP programs to get you started. Not knowing about AOP, but knowing a little about Spring.Net, I found this enough to start an AOP-based logging system.