Too true!
Even if I had a system that would repeat my performance of last year, I would spend most of my time look to improve it and find new approaches that would beat that performance.
A big chunk of my profit last year came from one trade. Almost exactly 12 months ago, I bought the Dow at £10 per point. After it had risen about 300 points from my entry, I did the same again. My position eventually grew to £50 per point. I lost my nerve after a few weeks and took some profits, but am still in that position today at £20 per point. With hindsight it seems easy!
The rest of my profit came from spreadbetting a number of stocks such as William Hill, Enterprise Inns, Man Group, mm02, Reuters, Cable & Wireless.
I did pretty well in 2002 when I went short the FTSE and Dow in April/May when they both fell through resistance.
Hope that helps.