Umm...okay, here's the thing, this is not how to properly tune a guitar.
I have given a few lessons to novice guitarists and one thing I have noticed is this: when I hear a beginner pull out his/her beautiful new guitar and play, (s)he is almost always out of tune. Ack! No matter how well you're playing, you just can't sound good if your guitar isn't tuned properly.
If you asked me yesterday why beginners are often out of tune, I would say it is because they have not been taught how to correctly tune a guitar. But after reading fricto's node, I might now say it is because they have been taught...
How to tune a guitar incorrectly.
What you shouldn't do is tune the guitar by comparing open strings with the adjacent and lower pitched string fretted at the 5th position through the strings. This is because all errors you make in the tuning process will be compounded, just ask an experimental physicist. You won't ever tune two strings to exactly the same frequency, so by the time you've gotten to the last string it probably won't be well in tune with the string you started at. Even when you use this method and have gotten each adjacent strings as in-tune as your ear can resolve, when you strum a full Emaj chord I bet you can tell it still doesn't sound just right.
The second popular method, which is actually what I hear most people doing, is another example of how not to tune your guitar. This is when one compares the 5th and 7th harmonics on adjacent strings, and tweaks the tuning pegs until the beat cancel disappears. I wonder how many guitarists are there in E2 reading this and asking "ay! What's wrong with this way, it's how I tune up!" The vast majority of people don't know that this will not really work. The reason for this is that your guitar is designed and built as a tempered instrument, i.e. it follows the tempered tuning, rather than the diatonic tuning. To tune perfectly to the 5th and 7th harmonics on your guitar will mean, strictly speaking, that your guitar will be out of tune.
Note: I believe the second method is actually acceptable, and I sometimes use it, for tuning an electric guitar - the reason being that a lot of rock music with a distortion pedal really doesn't require your guitar to be well in tune. Plus, it's easy, and when you're playing with other people you really need to get them to SHUT UP if you want to tune your guitar perfectly - and this can be quite difficult. =)
How to tune a guitar correctly.
If you're just going to play RATM and stuff, you can probably get away with a combination of the above methods. But if you're getting into classical guitar, which I strongly recommend you give a try, then you will need to adopt a more formal approach to tuning. Actually, adopt a more formal approach to guitar playing in general. Flamenco, tango, and the various other forms of exotic guitar are, as a rule, a great deal harder than anything you'll hear Tom Morello play. My friends think I'm the local guitar guru because I'll play any RHCP song they can throw in front of me, but I still struggle with brazilian guitar - those guys are guitar virtuosos, incredible.
Right, the first step in tuning your guitar is to get a reference point. Ask your sister to play you an A on the piano. Or get one of those blowpipe tuning things, dunno what they're called. Or you could buy a tuning fork - The one you want for your guitar is A:440 Hz. Tune the 5th string to A at 110 Hz - use the beat cancel. Note that this step is not really necessary if you are just playing solo, all you really need is to have the guitar in tune relative to itself.
Now that you have tuned an A, you mustn't alter the pitch of that 5th string. You need to tune all the other strings relative to the A.
- Tune the 6th string by fretting it at the 5th fret and comparing it with the open 5th string.
- Tune the 4th string at the 7th fret to the 12th fret harmonic on the 5th string.
- Tune the 3rd string at the 2nd fret in the same way (to the 12th harmonic).
- Tune the 2nd string at the 10th fret in the same way.
- Tune the 1st string at the 5th fret in the same way.
Congratulations, you should now be in tune. Hurl faeces at all those other idiots who haven't read this node, and pay them out for not knowing how to tune a guitar properly (hardly anybody does).
Now you just need to learn to play well.
srkorn: Ooh yeah, a floating whammy is a downright bitch. I hate those things. My electric (tigger) has one, which pisses me off since I love alternate tunings and can get whatever vibrato I might need with my left hand anyway (whoah, that sounds masturbatory).
Wim's homebaked solution for people who have got the shits with their floating bridge (I did this to tigger and the floater is no longer a problem): Unscrew the back panel, jam a fat chunk of wood (or something) behind the metal bit, as tight as possible. This will crudely force the bridge back, and you don't have the annoying floating bridge side-effects anymore. Of course this also means you can't play star spangled banner like Jimi anymore. =)