First of all you have to decide what kind of music you wanna play so you decide what type guitar you will get (acoustic or electric)

I am into metal so I started with electric but they say it's better to start with acoustic.

After you decide that you have to buy your own guitar. Of course if you can get a free guitar from a friend/cousin etc. go ahead but it feels different when you go and choose it on your own.

Getting a teacher is always a good thing but if you don't want to waste much money... Then you can start learning the basics using some good sites like this: http://guitar.about.com

Then you should get guitar pro (http://www.guitar-pro.com) and get the tabs of your favorite songs and start practicing and practising.

The best site in my opinion to get tabs is: http://www.ultimate-guitar.com/ and it also has some lessons.

You can also get a bunch of tabs in one file using torrents or p2p programs. Check this out: (http://www.torrentz.com/search?q=guitar+pro+tabs)

Finally, watch videos. YouTube will be your best friend for this or again you can get many learning videos from torents and p2p programs.

Keep playing and always have fun!