Turn up your amplifier. A good power metal song is best played with the volume is up. Power metal songs are not typically complex, nor do they need to be perfect musical compositions. Volume is a tool when it comes to playing power metal songs. Playing at a high volume level adds the crunch typical of power metal.
Learn power chords. These are staples of the power metal genre. Power chords are simple two- or three-note movable chords that allow power metal players to shift between chords quickly. Power chords also provide a wider musical canvas for guitar players to improvise solos over. Any beginning metal method book can teach you how to form a power chord. You can also find a power chords dictionary online free of charge.
Experiment with different rhythms. The straight eighth-note rhythm is a staple of power metal. To play a straight eighth-note rhythm, use a three-chord progression; C, G and A power chords are good starting chords for a beginner. Start on C and count one and, two and, three and, four and. Play each count with a downstroke. Switch to G and repeat, then switch to A. You'll hear the chunky rhythm found in a lot of simple power metal songs.
Record your chord progression and use it as a backing track so you can practice creating your solos over it. Try creating a solo over the chord progression using string bends and pick slides. You accomplish a string bend by playing a note and pushing the string up or pulling it down. This raises the pitch of the note you play. Combine these bends with pick slides. Accomplish a pick slide by dragging the edge of your pick over the strings of your guitar. You can drag slowly or quickly, depending upon the effect you want. Think of a pick slide as punctuation between musical passages you play on your guitar.