Each bumpy grass runway has it's own 'personality'. If you haven't landed on a particular strip before, be prepared to be bounced into the air at around stall speed, either on landing or takeoff. Not so much of a problem if you're expecting it, but can be on a new runway. Just keep the weight off the nosewheel as much as possible (if you have one) - the 'oildrum' sound in a Pa28 is a dead give away that you need more back pressure.
I'm learning on grass and have problems with perspective and height judgement when landing at large 'international airports'. Guess it's just down to experience.
