Why and How to avoid Event Handler memory leaks?

Question

I just came to realize, by reading some questions and answers on StackOverflow, that adding event handlers using += in C# (or i guess, other .net languages) can

Answer 1

Yes, -= is enough, However, it could be quite hard to keep track of every event assigned, ever. (for detail, see Jon's post). Concerning design pattern, have a look at the weak event pattern.