Its always important to define your 'circle of competence', in addition to that, its even better to understand your limitations. Look, I'm a 24 year old guy, been investing for 4 years have some experience looking at stocks and listening to analyst calls. But thats about it. Making huge calls on where the economy is going and predicting earnings on complicated companies are wayyyy out of my depth. Of course that means passing up some (alot) of opportunities here and there but its fine. I'm perfectly happy to sit still and do nothing, then assuming that i know everything. So here's a list of industries that I don't invest in. Banks Besides the line 'the P/B ratio of Sg banks are now < 1, the first time in 5 years or whatever' I have no other good reason to invest in them. Do I have a clue where NIM's are ......