Turn one
Ideally, a Ghitu Lavarunner on turn one is the best play if you're going first. It will often allow you to ping in for a couple points of damage before the opponent gets set up, and can often be a 2/2 by the second turn. Best of all it turns the 4 copies of Wizard's Lightning into Lightning Bolts, which makes counting to 20 much, much easier.
If you're on the draw, Lavarunner is still usually the best play as at the very least it gives you a 1/2 blocker. However, if the opponent plays Llanowar Elves on the play it's often the better play to Shock or Shivan Fire it. The deck can't deal with an early Gigantosaurus or Ghalta, Primal Hunger from Stompy decks, so deal with the dorks before they get a chance to snowball into big mana.
Turn two
Runaway Steam-Kin is without a doubt the deck's best two-drop. If you have it, cast it, as by the next turn it may well be a 4/4 that can lose counters post-combat to pay for a Risk Factor.
If you don't have it, options remain plentiful. Viashino Pyromancer is solid, as a free Shock with an aggressive body helps keep pressure on the opponent's life total or provides a blocker that can trade up. Lightning Strike and Lava Coil are much more situational, but if there's a cheap creature that might become a problem later (such as an opposing Runaway Steam-Kin, a Siren Stormtamer or a Goblin Electromancer) feel free to blast it.
Lastly, a second Ghitu Lavamancer can still be a solid play on turn 2. We want to keep pressure on at all times, and if we burn the blockers away attacking with a pair of 2/2 creatures over several turns will add up.
Turn three
Guttersnipe, baby. All day every day.
If not in hand, repeat as above; small creatures and burn spells. Always keep pressure on, whether by killing creatures or damage to the dome.
By this point the hand is usually running light, so if possible, you can Risk Factor. If the opponent hasn't taken too much damage yet they'll usually choose to take 4 damage, but this is fine - we can jump-start it again next turn. If your hand is running really, really light, The Flame of Keld is generally worth playing to get 3 cards next turn, even if you have to discard something of value.
Turn four and onwards
Basically, just repeat the above steps as appropriate. Under ideal conditions the game shouldn't go far beyond this point anyway. Keep chipping away at the life total, play Guttersnipe in multiples where possible for extra damage, and keep refilling your hand.
Sometimes the game will get bogged down, which is where the single Rekindling Phoenix comes in handy. 4 damage in the air per turn speeds up the clock significantly, and in an emergency it can do a decent job blocking a Tempest Djinn.
