Since I've held the record for long enough now, I can give you lot some clues:
1. You need a flat surface less than 9 blocks wide that will NEVER BREAK. This is the most difficult part.
2. Never put the S, Z, L or J pieces sideways, unless you really have to. the other part shifts when the other part is destroyed.
3. You can push the J L and I blocks against the wall and get some time to think.
4. Like in poker, you have to fold and quit most of your games. You'll know when things go wrong. But if you've got a lot of points, try to make a new flat surface and salvage what you've got!
5. While it's possible to get 4 lines at a time, you should only try 1 or max 2 lines at once. Otherwise the neat order you've been building will most certainly get destroyed.
I haven't played this in a while but I'd love a challenger to the 66 lines ;)
You really should have read the book, there's some great ideas for a game like this, like a harpoon tied to a plank that'll tire the whale down. You can actually get a very well read audio book version for free from librivox.org!