There is a great way to move around Paris as a complement to Metro or BUS.

VELIB bikes! they are evywhere! Usually not more than two or three blocks apart.By paying 8 euros for the week you can use them free for 30 minutes and then you get charged for each additional half hour. You can buy the ticket (a code number and a password) online or directly at each parking spot. The website is : http://www.velib.paris.fr/ there is plenty of information on how to use it.

The best part is the APP Velib' that lets you know where are the parking spots in regards to your location and how many bikes available, and also if there are free spots to park (sometimes the location is full). 

The system is really very usefull as a complement to metro and BUS. For instance you can get down at TROCADERO station grab a bike and circle around the Eifel tower for half an hour or more and get all the views you want. You can bike all around the "Quartier Latin" and Boulevard Saint Germain ending at Notre Dame. It's really fantastic and cheap! Great in combination with a PARIS VISITE ticket that lets you use Metro and Bus for several days. You can also walk but the bike lets you move faster and see more. Imagine youself going along the Seine river in a Bike. Or around ChampsElysées.

Some simple precautions:

1.- Try to avoid crowded streets. Pedestrians are terrible, specially in very crowded tourist spots. High trafic streets are also to avoid, but generally not terrible.

2.- The bike has a basket and a lock, use them. Keep your valuables secure. Paris is full of pick pokets.

3.- Don't go to a spot with 1 or 2 bikes. They can be flat tires.

4.- Always check the bike you are going to take before. If it doesn't work you'll have to wait some minutes before renting a new one.

5.- When giving back your bike, check that it is loked and THE GREEN LIGHT IS ON. Otherwise you can be charged with a warranty.

6.- Don't try to force the bike out when renting, you just have  a few seconds, and sometimes they require lifting a little the back wheel to move out. If you get desperate and force it you'll loose your time and it wont come out.

7.- Try not to exceed the half hour, it cheaper to change bikes. Remember the first half hour is free!

8.- Having a helmet is not a bad idea. You'll feel, and be safer.

With theese simple tips you should be able to enjoy a good ride. Remember, this is help on top of other transportation systems, for short rides. But it's very usefull, cheap, and simple to use.