This bulleted list introduces things which made our trip much easier.

• Santa Claus brought two excellent pocket sized Frommers guides (London/Paris) which served us well when navigating such vast attractions and city transit.
• In London we used peak time Travelcards which were excellent for getting around above and below ground. In Paris, we purchased two carnets of metro passes which lasted the duration of our three day trip. Good value.
• We gained, through our choice of traveler's credit card, automatic medical insurance while abroad and felt very secure. Don't forget to insure yourself.
• We traveled in an incredibly light manner. Small knapsack each. Although space was limited, our ability to move around the city (and especially through airports and customs) was greatly improved. Had we desired, we could have mailed anything beyond capacity home ahead of us.
• Create for yourself a log book to warehouse your important travel documents. My book had an itinerary, budget, checklist, attraction and ticket confirmation numbers, copy of passports, reservations, specific maps as well as on site information to support visits (ie: Items I wanted to see at the Louvre). It also had a sealable plastic sleeve for tickets/receipts. I looked and felt very organized.
• Check with your card company before leaving so they know the card may be used abroad. Nothing worse than spending valuable travel time sorting out banking issues.
• Order foreign cash at your bank before you depart, as last minute attempts to purchase currency risk amounts not being available.
• E-mail home was simple through terminals available at most accommodations (may cost but fees minimal).
• Make sure that you take a comfortable, tried pair of shoes (we walked miles in the Louvre itself)
• We stuck to bottled water and had no "compatibility" issues