great thread. ive been fortunate enough to be an internet junkie (thank god for scubaboard) and also live in FL with plenty of tech divers around at LDS' to talk to learn what not to buy. the snorkel thing i saw coming waaay off. bought a $3 collapsable one at a tent sale for the course and doesnt take up much space in the bottom of my gear bag where it only comes out when i want to pretend im a pirate with a telescope (land-ho!). the tank banger on the other hand, i had to learn the hard way. i havent rushed to buy any gear since i dont want to buy gear twice.
worst advice ive been given was by a tech diver (LDS co-owner) who suggested that i not worry about getting technical gear (bp/w, din regs, etc), even though i plan to go limited tech, and just buy all recreational gear now since ill have to replace all my gear once i go tech...i quickly informed him how retarded his rationalization was.
second worse was from a kid behind a counter at another LDS...i was in a rush at the same tent sale at closing, and he tells me, when i couldnt get the akona wetsuit i was trying on to zip up, that "wetsuits arent really meant to be zipped up on your own - your buddy is supposed to help." MADE them give me a credit the next day after buying the awesome o'neill i have now at another LDS for $100 (which, btw, zipped up flawlessly).
as a new diver, what ive learned the most is- if it sounds stupid, it probably is. do your research and never take any ONE persons advice.