I found this interesting article - some really great tips on investing I heartily recommend anyone looking to build up a portfolio themselves to take a look at:

Vanguard − Six investment pitfalls: Are you falling into traps?

Key pointers:

1. Investing without a plan
2. Underestimating the impact of fees and taxes
3. Selecting investments before asset allocation
4. Chasing performance
5. Trying to time the market
6. Not rebalancing your portfolio

That's a good article. Most of these seem like common sense, but we often forget it and break many of these fundamental rules. I respect Vanguard and find their work to be of high quality.

It's really made me think more carefully about different issues, too - I often find myself making quick decision at work without planning ahead, but if I took this attitude to investing, I could end up with a seriously unbalanced portfolio.

Thanks, I needed to take a moment to think about what mistakes I might be making and then make concious moves in the right direction.