Back sometime in 1999, aged 13, my first ever 'trades' - went long Atlantic telecom, doubled my 1k overnight and took profits, after a few weeks, doubled my money on Cable and Wireless, banked another 1k. I was immortal and only 13..
Fast forward a few months, scaled up big time using my new spread betting account with Cantor, i'll put on another trade in my *lucky* stock. 40% gap down overnight, £1,600 loss and growing!!! and I still haven't learned to use stops! :-(
A couple of years later I got heavily involved in day trading the FTSE & Dow. Thought I would try my luck on the S&P500. Added a some extra digits on the 'pound per point' to gain sufficient exposure, unknown to me that it was pounds per 0.1! Anyway, down hundreds within minutes and about to get a margin call. I left my position open, came back 2 painful hours later to a tidy profit of £600.