Learning How to Speak French before traveling to Paris can be a rewarding, not to mention useful enterprise.
A little time devoted to learning a few basic phrases can go a long way in helping you enjoy your vacation even more. As tempted as you may be, try not to let your first words be "Do you speak English?".
As an absolute minimum, learning the simple things such as "hello, excuse me, please, thank you," should help ease your way into a new culture wherever you travel.
Start your conversation in French. The French will appreciate your efforts and show a willingness to help you. They will also know right away that French is not your first language and will most likely respond in English themselves.
Smile. Be polite. You will win them over by your efforts.
And don't be offended, if after long efforts in learning your French phrases, you are answered in English. The French are very particular and can tell when a speaker is native or not.