[StavrosK]

Step 1.5: Use something that overwrites everything, for good measure. I'd say this is more important than #1, since encryption is more likely to fail than overwriting (I once discovered that my encrypted volume had actually been set up as unencrypted, and I wasn't encrypting the things I thought I was).

[pktgen]

Yep, write random data to the entire drive before doing the secure erase. That way, even if the secure erase implementation is completely broken, at least the remaining data should be limited to the spare area of the drive.