(Thug life! There's no way a Parisian driver won't see me)
When the weather's good and the Métros are too stuffily hot or crowded to bear, the absolute best way to get around Paris is in the Vélib'. This clever bike-sharing system makes wheeling around town easy and, best of all, affordable. There are over 1,200 Vélib' stations and 18,000 shared bikes in Paris, making it the world's 3rd-largest bike sharing system. It used to be a hassle to use the bikes for just a day, but now you can take out a bike on a one-day pass for just 1,70€.
First, sign up with your credit card on the Vélib' site. If you'll be tooting around town for more than a few days, you can also sign up for the 7-day pass at just 8€ or a year for 29€. Choose a PIN number you'll remember, and then you'll get a confirmation email sent to you with a code. Write down this code! When you find your nearest station, you'll follow the directions on the screen to log in. The first number you'll enter is your confirmation code. Then you'll enter your PIN. Choose a bike and it'll be released to you. If you keep your ride under 30 minutes, you're good to go. If you go over 30 minutes, you'll be charged 1€ per half hour. So I'd recommend that even if your journey isn't over, find a Vélib station to enter your bike into, then take out another one to keep costs down. You could bike all over Paris for less than 2€ this way. The great thing is that even if you can't find a station that has a bike or available spaces, each station is equipped with a map of the five nearest stations in the area.
Note: Observe all Vélib' guidelines about checking a bike in and out. Before you take out your bike, check to make sure both tires are inflated, the brakes work, and that you have two pedals (seriously, I checked one out once that had no left pedal). Be safe - if you live in Paris, invest in a helmet (you can see from the photo above that I've selected a very adorable pink plaid helmet). Stay alert, obey all rules of the road, and heed the power of maniacal Parisian drivers. Also, the bikes have the cutest bell - don't be afraid to use it when necessary.