I've been playing the guitar for 6 months and I've come to really enjoy playing. I'm really dedicated in my guitar-playing and i was wondering what key things i should know about playing better. I really need tips on how to tune the guitar by ear :P for example.

i need to become moar gud lolz srsly.
buy a tuner or tune after the A note on a piano, thats what i do..

well in order to improve your skills you just have to want it bad enough.. it's practice! and lots of it
tuning the guitar by ear will come as you play the guitar more, you could try practising tremelo picking, legato these things will help you become a better guitarist/musician
Just keep practicing. My friend is amazing at guitar and she is self-taught, and her advice is just practice all the time and experiment with different styles and sounds when you feel comfortable with the basics.
Basic theory and an understanding of the major scales will help you lots as well.
Practice, practice, and practice more. When you think you've practiced enough for the day, keep practicing. Practice even more. Only when you CAN'T play anymore, than practice a bit more, and so on ...

It's all about practicing enough and effectively.
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