Can I get some positive advice?

I had a butcher tell me to sear both sides and then finish on low about 15 mins a side. To me it seemed burnt and over cooked. Now I pre-heat the grill and cook it on low for about 10 min a side (depends) but then you gotta let it rest for at least 10 min. Slice thin and enjoy! Hope it helps.

Reverse sear is the trick that works for me. Made this one last night!
http://www.bbq-brethren.com/forum/showpost.php?p=2477981&postcount=1

works for us

Cover tri tip liberally both sides with kosher salt for one hour wrapped in siran wrap and allow it to come to near room temperature. After one hour rinse all the kosher salt from the meat. Apply salt free seasoning is: lemon pepper or garlic pepper, or just rub the heck out of it with fresh garlic. Sear on high heat 3-4 minutes each side (bring it to medium rare). Remove from grill and wrap in foil (shiny side against the meat) for 20 minutes. Cut against the grain.

you are great, you are handsome, you are talented, and you know what, you are a fine pitmaster, yes you are. you can do it all, and it...or, you mean on how to cook a tri-tip.

well...

First off, I really like to find a good Choice grade tri-tip, and if it has a tail, I tie it back, like this...

Makes for a more consistent cook without the little end getting too dried out.

For a rub, you can use one of the commercial ones, such as The Rub Company Santa Maria, Suzy-Q's Santa Maria, Dave and Barney's or you can throw one together. My basic Santa Maria looks like this:

3 parts kosher salt
2 parts medium grind black pepper, no dust
1 part each granulated garlic and granulated onion
1/2 part ground chile, powder from Ancho is nice
1/2 part dehydrated parsley

Just toss it all together in a shaker. You are good to go. Note that there is no paprika or other unusual spices, the flavor profile is pretty straightforward. Personally, I also add 1/16 to 1/8 part of sugar, not for flavor, as that will not be there. But, chemically, it helps the rub.

As for the fire, a lot depends on your pit and comfort zone. On my Kettle, I normally go indirect, 250F or so, until it temps 120F internal. Then I sear. When I feel like paying attention, or am working on a cooker with an adjustable grate, I prefer direct fire, still in the 250F range. This will cook the same time, but, does not need the sear process, so I cook to 135F internal and am done. I rest for 10-20 minutes, tented in foil. I generally shoot for a product like this...


Note that I don't like the outside to be blackened or charred at all, I prefer a more tender, caramelized surface.

I'm a fan of the kosher salt dry brine but also add the garlic at that time to. The salt will pull it into the meat also

i actually like to coat mine with mustard. then some salt and pepper. maybe some garlic powder. cook indirect till about 125-130 int temp then direct to char things up a bit. no more than about 4 minutes a side and thats just the two main sides.
around here they also cook till done through but thats at much longer cook over coals but at a much farther distance like on a santa maria grill. if done properly this way then its also soft. i do it the first way cuz i have no patiance for the later.

I marinate in Ibarras teriyaki overnight, give it a quick sear over direct heat, then indirect until she reaches 125-130, let rest 20 minutes and slice thin although I'm going to try the reverse sear on the next one.

A contrarian method, which I have used to good effect when cooking for folks I know like less tender meat (which I know sounds odd, but, actually, many of the farm and ranch folks I know do not like 'pink' meat).

Prepare a marinade of 1/2 cup Italian salad dressing and 1/4 cup BBQ sauce. I like Sweet Baby Ray's. You could also just add some ketchup, molasses and Worcsestershire sauce to make 1/4 cup total. Place tri-tip(s) and sauce into a vacuum bag or ziploc (vacuum sucker is better) and get all of the marinade in touch with the meat. Let sit for 24 to 72 hours.

Get a direct grill hot, to medium, and grill direct until lightly charred on outside and inside is done to temperature. I still like 130F internal, but, when cooking for others, 140F is pulling temperature. Then rest, slice and bask in the glory.

When I was in the biz, we used to marinade them in Soy, Garlic Powder, Pineapple Juice, and Ginger. They would live in a hotel pan for nearly 2 weeks, the longer the better for my taste. Then flash them on the char-broiler and rest and slice super thin. Then cook mediums to wells in a skillet with marinate. Of course this was high volume, similar to Chuck's Steakhouse.

the first landarc post is the way to go!!! skip all the special marinades....