If it is your first tri-tip, go with smoking it indirect until internal reaches 110.....then sear that bad boy to just under 130 and pull it off and foil tent it for about 15 minutes.
If you want the full on Santa Maria experience, rub it with salt,pepper and garlic. Use red oak for smoke and heat....outrageous.
Then........your next cook, succumb to the call of the Trisket