Here's a few:
I found the bulb mode+remote switch combo the best, better than pre-setting the exposure, this way you simply press when you see the rocket rising and hold until it shines. I was in a bad location, couldn't chose, so the background is not so nice, but I still love the shots.
Also, I cannot emphasize how important was the purchase of new, bulkier and heavier, but also much more stable tripod. I was on a top of a building, pretty windy, I know my old tripod would wobble under the weight in such winds.