It's all in the wrist. I know most people will like twitch your whole arm, but that's the wrong way. You may be able to play fast, but you don't have control.
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a lot of practice and a metronome


+*large number
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I hate that...actually I just hate anyone under the age of 16

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Just get it cut a little. It will grow back. Besides why is it so important to look metal? That's just retarded.

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Practice mostly. Work on fast 16th and 32nd note picking first, and tremolo picking should come easy. Be sure to use a metronome when you work on stuff like that though
Ideally you want a floating picking hand (no part of your hand is anchored to the guitar. your arm is fine) and you want all the motion to be in your wrist. Angling the pick can also help.

Once you've got your posture sorted just get a metronome and practise.

And do something with your fretting hand as well; you want to develop your hand synchronisation as soon as possible.
Use the least necesary amount of motion, a major problem I had at first was that I'd start flailing around if I wasn't paying attention, hitting other strings....a no go, of course.
Start it slowly until it's perfect, it's no use being able to do it fast but sloppy.
To be honest, like with many techniques, there is just no way for someone to tell you how to do something. It's just one of those things you try out one day and all of a sudden you're like "OMG....I can do it!".

Then, once you can sort of do it, you can start to make sure you're doing it right, i.e. using wrist and not whole arm.