These are some of the things I learned:
Invest in a brolly -- best 5 euros spent in Venice as it insured us against rain.
Check websites for opening times but then phone them up as well as the two yarny places we visited in Devon were both closed in spite of aforesaid website information.
Don't wear a beaded jumper to go through security at the airport (the last time I wore it to go away airport scanners weren't as sophisticated!
You cannot do an infinite amount of knitting or crochet in a finite amount of holiday so leave space in your packing for clothes as well.
And finally, It doesn't matter where you go, it's who you go with that makes the holiday!