I've learnt some good stuff over the years:
Your investments should have a % of bonds equivalent to your age.
Individual stocks are more risky than funds.
Buying and holding for the long term doesn't seem to work any more.
Drip feeding money into funds on a monthly basis works well.
At the moment I'm trading bank shares (especially Lloyds), and trading in and out of commodites where I can see a good chance of a steep rise or fall.
Buying and selling the FTSE during the peaks and troughs would probably work out well for a pension as well.
ETFs are also good for short term trading as there isn't any stamp duty on purchases.
I'm liquidating my other personal pension to add to my SIPP - it's slumped 10-20% this year, my SIPP is up 10%.
I don't plan on trading very often - in this game you are playing against some of the brainiest people on the planet and they will gladly take your money (as I've found out in the past).