You don't have to wait a year in order to begin playing easy metal songs! Once you can play power chords and apply picking patterns over them, you're armed and ready to go.
Below is the list of easy rock/metal songs that came on my mind. They are supposed to be played with distorted or overdriven electric guitar sound. Tips on tweaking distortion effect are here -->.
Note that despite the riffing isn't difficult in these songs, almost any guitar solo is really difficult. So ignore solo parts you'll see in the tabs.
Holiday- Green Day
A few power chords and very simple rhythm that do not require speedy hand make it very easy song to play.
If you'll find the INTRO difficult, just substitute it to the main riff, sounds very similar anyway.
Smells Like Teen Spirit - Nirvana
One of the most famous grunge song in the world is one of the easiest to play too (including the guitar solo). Actually I think it's the easiest guitar solo ever. Play the VERSE with a clean sound and fire up distortion on the CHORUS.
Hot - Avril Lavigne
The song is not difficult but fun to play. The Interlude in the tab may seem slightly complicated, you can just play A#5 - C#5 - G#5 - D#5 power chord progression instead.
Crazy Train - Ozzy Osbourne
Here you'll need some more practice though, because in the main riff between the chords there are fast palm mute notes that you'll need to pick accurately.
I noticed that if to skip playing the 3rd notes in these chords which located on the B string the riff will sound about the same but becomes heck more handy.
Change - Deftones
This tune is really "hot". In order to play it you'll need to drop the low E string to the note of D. (You can always verify the D note by checking it with the open D string).
Sanitarium - Metallica
It's not difficult song to play if you skip fast bridge riffs in the middle of the theme. You can also modify chorus riff by escaping fast muted notes and let the power chords ring instead of them.
Open Songs for Beginners Page
Songs in this list are based on open chords, strumming or finger style, and supposed to be played with the clean electric or acoustic guitar sound.