I am not a travel expert by any means, but the husband and I learned a few things on our trek through northern Europe, so I thought I'd share them with you as I fly (the looooong flight) back to Seattle.
-- pack for varied weather. No matter how often you check weather.com for weather predictions for your upcoming trip, things can change. Unless you're going to Italy in August, be prepared for all weather. Even snow in London in April. ;)
-- pack less & bring detergent. We were gone two weeks but packed clothing for one week and did "laundry" in our hotel and rental sinks. It works well and saves on space.
-- pack solid shampoos & conditioners. Liquids are limited, even when you check bags. And traveling with liquids is always a pain because they can leak and get everywhere. I splurged on Lush solid shampoo and conditioner, but amazon also has some other options.
-- snacks! I packed instant oatmeal, individual packaged peanut butter, granola bars and dried fruit. This saved us during flights and long train rides. We also restocked on snack foods about half-way through our trip.
-- research! Each place we went to, I tried to research transportation options, a few restaurants and sights to see. In regards to transportation, find the cheapest option obiviously and see if there are visitor passes for the public transport. (In Europe, there nearly always is.)
.... also, be sure to research local restaurant and other courties (i.e. when/how much to tip.) :)
-- talk to locals. Ask them where they think you should eat, what you should see. This led us to some of the best cafes during our trip! If no local can be found, tripadvisor.com is a great resource for restaurant/tourist attraction reviews.
-- airbnb. Although it started with a snafu, the flat we rented in Paris was awesome and affordable and really felt like home in the middle of our trip. Plus being able to cook rather than going out to eat, saved us a lot of money. Just to add, if something does happen, airbnb has awesome 24/7 customer service and does refund money if your situation goes a bit sour. ;)
-- keep a journal. The husband and I kept a daily journal that we taped little souvenirs, brochures and tickets in. It's old-school but I know we'll treasure it forever.
do you have any trips for international travel?