I had some mnemonics for remember which way diodes go, unfortunately one of them is wrong. A diode is a junction of two doped regions of silicon. There's a positive (p type) silicon region which has a surfeit of holes due to it being doped with an acceptor substance, such as boron. Then there's a negative (n type) silicon region which has a surfeit of electrons due to it being doped with a donor substance, such as phosphorous.
p-type = acceptor
n-type = donor
p-type ≠ phosphorous
n-type ≠ boron
which would have been really handy.
At least there's a handy mnemonic for remembering the direction of current:
holes float up the electric field gradient
electrons roll down the electric field gradient
I hope so anyway, as that's the way I remember it.