Originally Posted by GuitarBizarre

Don't worry yourself too much about it. Nobody can do that at first, it took me a year before I could tune accurately like that, its just a matter of getting your ear in.

Some tuning tips -

Always tune going upwards. This stops the strings from snagging going down and ensures it stays in pitch more stably.

Make sure you're not putting too much pressure on the strings when fretting. This will send them out of tune.

Do it with distortion on. If its out of tune, you should hear the sound 'pulse' and 'beat'. The faster its doing this, the further out of tune you are. Tune it until the beat stops. Same goes for if you play a powerchord, in fact, once you're familiar with the sound of a powerchord, you can tune by them just as well as by 5th frets.

Make sure your tuners are tight enough. Most tuners have a screw head in the top. Tighten that up. Don't strip the thread, but make sure its not loose. this will keep things in tune as best as the tuner is able.

Also, even if all of your strings are out of tune, you can still tune the guitar to itself. It won't be in tune with anything ELSE, but it will sound good when played on its own. If you want it to be in 'concert pitch' then its easy, just find something thats already in tune (Piano, keyboard, download a recording of a recognizable pitch, anything will do as long as you know what note it is. I know some people who can tune from the pitch of a dialtone.)