How Not to Forget Things
You know who you are: we make lists, others make lists of lists, some use yellow “sticky” notes, some pack a week in advance and live out of the suitcase at home for a few days to see it they brought the right stuff and nothing more.
A Large Box
A less dramatic tip is to set a large box aside and put things into it in the days before your trip that you'll know you'll need but don't want to pack just yet. For some items you may want to just write the item down on a slip of paper and drop it into the box. Then, as you get around to sorting out the actual items you can remove individual pieces of paper to be replaced by the actual thing.
It seems to work better than a list for some people. The kids can join in by drawing pictures instead of words on the slips of paper.
The “Drop Dead” List
We have what we call our “drop dead” list, things we ALWAYS triple check we have: passports, tickets, credit cards and money. Our feeling is that if we have nothing else but the clothes on our backs, we can still travel at some level with just these “drop dead” items. Add things like necessary medicines to make your own list. Don't let the list get longer than you can easily memorize.
Don't hesitate to use the drop dead list while you are out wandering around Europe. Run down the list when you get up to leave a restaurant and before you jump off a bus. We spent the equivalent of what seemed like ten person years returning to places in London where we left our daughter's favorite sippy cup before we, reluctantly, added the darn cup to the drop dead list (we still have it, though she has grown into using the more prosaic glasses any restaurant uses. Ah well).
We buy separate small bottles of shampoo, new toothbrushes, that kind of thing so that we can pack the toiletries the night before and still brush our teeth on departure morning without worrying about trying to remember to pack the toothbrush after we brushed. The little travel-sized bottles also somehow seem more fun to the kids.