Safety, politeness, and the rules of the road
Buy a warning flag ($7, any bicycle dealer) before you leave Canada, and attach to the left-rear of your bicycle. Bicycle flags are not common in Europe, if they exist at all, and attaching one to your bicycle will make you conspicuous to motorists. Not knowing quite what significance to attach to the flag, motorists will tend to give you the benefit of the doubt - and consequently a wide berth when passing!!
When asking for directions or help, presage your question with a “Bonjour Monsieur/Madame, s’il vous plait, (parlez-vous anglais/pouvez-vous m’aider/ou est le boulevard Voltaire)?”. Not to do so may result in your being ignored or even given a dressing down (happened to me in more innocent days!).
Other than England, traffic in Europe is right-handed, and in this respect will pose no problems to North Americans. However, when turning right the crooked left hand signal used in Canada has no significance in Europe. Rather, extend your right arm to indicate that you are turning right. When turning left, make sure to look over your left shoulder to gauge the following traffic, and when giving the signal that you are moving into the centre lane or are about to make your turn be very assertive. Do not simply extend your left arm as a signal, but, while continuing to look over your shoulder, agitate your arm vigorously, as you extend it, with the index finger pointing backwards. This gives the impression to following motorists that they are being commanded to stay back while you make your turn, not simple being informed of your intention to turn. Motorists in general are not naturally accommodative of cyclists - they have to be told what to do! Make your move only when you are sure that you have got their attention.
Do not ever cycle on motorways, or on roads designated as Route Nationale if they can be avoided. Buy a map at least 1cm: 4 km in scale (e.g. Michelin Carte Routiere et Touristique, 1 cm: 2 km with relief) that shows all the minor roads and lanes that are available for cycling. In mountain regions however, you may have no choice.