I take a layered approach.
One password for all the stuff that isn't really important like sites I visit a few times and then leave.
One password for sites I trust and use on a regular basis, but where a compromised password isn't the end of the world. HN is in this category.
Seperate and strong passwords for stuff that matters, like netbanking, gmail, etc. To remember these I have a system set up so that the passwords are similar in a non-trivial way, like [first words of sentence][number I remember]. One password derived from this could be tqbfjotld!1249057, easily derived from "the quick brown fox jumps over the lazy dog!", and 1249057 which is the serial number for the motor in my boat. This way I only have to remember a phrase and a number I already know for entering secure sites.
Using this system I don't have to rely on potential unsafe software, or writing down passwords that may be compromised.