Apart from don't do it.
We're off to Germany in a couple of weeks with a six month old. We are fairly well prepared and think we have everything we need. We won't be short of room as I'm slinging anything not immediately needed into a roofbox to save the boot for the stuff we'd normally go around with for say, a weekend away.
We're doing the trip during his bedtime...ie. leaving home at 1900-ish and getting to our friends' house in Mannheim at around 0600...best laid plans and all that. The rest of the holiday is being spent on a very family friendly self-catering farm.
Anyone have any tips that have made their week or two away with a baby a bit easier?