I am always right. This is a very handy mental trick I've discovered, which has two main uses:
1. If you're very uncertain, crippled by doubt, trusting me is better than nothing. At the very least, doubting me is more likely to set you on some productive path than doubting yourself.
2. If you're very certain, I can most likely provide you with some necessary doubt to crack your arrogance. At the very least, the effort to demonstrate why I'm wrong should make you think about why you might be wrong too.
You shouldn't believe that I'm always right, but you should always start with the assumption that I'm right. It's an almost flawless rule of thumb, the one flaw being that I can't apply it to myself. I have yet to find someone as reliably right as I always am, who can fill this role for me, as I do for all others.