Ricdude's Tetris strategies:
1) In general, keep your field flat. If you have a choice between making a spike (e.g laying an L piece upright) or making a flat space (e.g. laying an L on its side), go with the flat space. Flat is easier to build on than spikes.
2) Know how to dig out the holes. If you bury a hole inside your field, figure out how you can expose it, so you can fill it with another brick. The T bricks are usually helpful here.
3) Look ahead. The "optimal" location for your current piece affects the placement of the next piece. Figure out if the new position for your current piece allows for decent positioning for your next piece. For example, you might be able to place an L upright next to a small hole, and interlock an upside down L on top of it, covering the hole, and making a nice flat space out of the remaining part of the field.
4) Tetris Or Die! (depends heavily on bonuses for scoring a "tetris", i.e. completing four lines with one piece, the I) If the bonus for scoring 4 lines is significant, leave a one space wide hole on one side of the field, and wait for the I to show up. Don't be afraid to let the rest of the field fill up, as long as you can prevent internal holes from showing up.
Keep in mind that if you're going for a record, you're going to have to take chances and capitalize on the opportunities you've created. Maybe you'll fill up your field almost to the top, and barely have enough space to fill in your "tetris channel", and they you'll get 4 I's in a row, and be back to a flat field. You're not going for a safe, mediocre, just keep the field in the middle, and knock out holes when you can get to them game. You're going for a record. That means you're going to miss that mark all but one time.
Prepare accordingly, and be prepared to nail it when the random brick order swings in your favour.