1.put your thumb at the back of the neck
2.start off slow
3.look up some children of bodom tabs and practie them
4.practise your picking http://www.myguitarsolo.com/gym4.gif
Take an arpeggio and start from the top or bottom of it. start slowly getting through the arpeggio with one solid morion of your right hand (sweep it!)
And yes us a metronome. Work on a couple arpeggios for a while and eventually you will master it.