Step 1: Find friends Download the Foursquare app to your cell phone and instantly link to your address book and Facebook and Twitter accounts to discover where your friends are hanging out. See if they're near you by looking at where they've recently checked in.
Tip If your phone doesn't have internet access and you live in the U.S., you can use Foursquare via text message.
Step 2: Check in Tell your friends where you are by checking in at one of the thousands of places Foursquare lists automatically based on your GPS location. Leave tips on special features you find around town and don't skimp on the details: inside information is one of Foursquare's best features.
Tip If the place you're at isn't listed, you can add it to Foursquare.
Step 3: Learn tips Check out tips from your friends and from the hundreds of thousands of other users -- find recommendations on your specific location or suggestions for things to do -- or avoid -- nearby.
Step 4: Get out The more you use Foursquare, the more you'll get out of it. Unlock badges and earn points based on where, when, and how often you check in -- see how many you can rack up in any given month, and check out your stats at foursquare.com.
Step 5: Gain power Check in at a location more than anyone else and become the mayor -- you don't get a key to the city, but you might get rewards from certain businesses just for being a loyal customer.
Tip Even if you're not the mayor, look out for specials offered to Foursquare users.
Step 6: Use it everywhere Use Foursquare wherever you go -- in museums, at airports, on public transportation, during concerts -- you never know when you might come across a little planned serendipity.