Tuning
Most heavy metal guitar players play in drop D tuning. The reason this is so popular is cause of the extremely heavy sounds you can get from drop tuning your guitar. For this exercise we will use the drop D tuning. To do that, simply place your index finger on the seventh fret on the top E string. Now pluck both the E string and the A string. With the seventh fret pressed, when tuned right these two should sound identical. See the picture below.

Power Chords
If you have never heard about power chords before then this is going to open up a whole new world in your guitar experience. Power chords are extremely easy to learn but a powerful skill none the less. As you can see on the images below, power chords are mostly know in two variations. The first one is mainly used on the top two strings cause of the drop down tuning, while the other one is used on the string below.


Palm Muting
Place the palm of your hand which holds the guitar pick against the guitars bridge while picking the strings. This will result in a kind of “damped” sounds. Try picking open E while palm muting the E string at the same time. Then try palm muting different variation of the two power chords.
After you start feeling confident with you metal skills, try finding tabs to some heavy metal songs you enjoy and try to play them. Don’t go ahead of yourself and go straight for some insanely fast metal riffs. Start with something easy and not too fast and then add more and more songs to your practice list and before you know it you should have mastered the basics of the heavy metal guitar style.
For those interested in mastering the heavy metal play style, take a look at this review of the Burning Metal, Heavy Metal Guitar Lessons.