Yeah, being able to tune by ear is important, but in most cases it's faster and more reliable to use a tuner. Some people are good at tuning using the 5th fret of the lower string to hear the note, and with this method you can get the strings all tuned to each other but if one string is off then no string is on the right note. When I use this method I usually end up in a perfect half step down. The guitar is all in tune, but not to the same tune anybody else would be playing in. And then you could use another persons instrument to tune your strings, and go from there....but seriously its much more convenient using a good tuner. However, as I said, learning to tune by ear is important especially since it allows you to learn notes so you can play songs you hear or compose your own. Keep on practicing, it takes a long time to really get it down, I still have a ways to go before I could say with confidence I can tune by ear and I've been playing for a while now.