If your waterproof jacket doesn't have a hood, take a mini-umbrella or buy one in Europe. Bring gloves and some kind of hat. Wear shoes that are water-resistant or waterproof. Or buy European clothes soap that comes in a tube complete with scrub brush built into the cap. If your sink lacks a stopper, pop a film-canister cap in the drain.
Square bottles fit together well, taking up less space than cylindrical bottles.
If you usually take a pill before bedtime at home, you'll need to take it first thing in the morning in Europe. Remember to bring the pills on the plane each way to take at your home dosage time, too. You don't need to bring a bar of soap - most hotels provide a small one. Bring an empty travel soap holder and just save and reuse the hotel's freebie bar. Bring a sunscreen that doubles as moisturizer.