Amen about the margin. I went on margin to buy a stock that was under the threat of an absurd lawsuit -- but a sketchy and unsigned offer sheet that had "Unbinding" written across the top of its full 2 pages was deemed binding by a Delaware judge (may he rot long in hell). The company I'd invested in went bankrupt. I went from having $1.5 million to under $25,000 in holdings.

This has made me somewhat evangelical about margins.