The joys of winter flying and an aircraft parked outside. I don't scrape off frost, if it's that bad I fly another day. If covered in frost and sunny, that's a different matter, turn into sun, brick under nosewheel, it soon melts. Don't see that you can do much about the water in fuel bit, other than be aware if it's an aircraft that often has water in the fuel when preflighting like the one I used to fly, it could be frozen. The one I'm flying at the moment I have never drained water from it's 13 drainplugs, but that doesn't mean it will always be that way. I suppose the only sure way is not to fly in these conditions, but that's a bit drastic.