Use a 60 40 mix of cooking oil and apple sider viniger. Spray it on the meat roughly every 30 minutes. Keeps it moist. Also. Put a pan of water in the smoker/grill what have you. To help keep it moist.
Ill have to try the apple cider and vinegar. When we use the smoker we keep a pan of water in there. This is just cooked in our BBQ and done in a few hours.
We started cooking a tri tip on the top rack today around 3 pm. Pulled it off the top rack at 4:50 at 160 degrees. It was marinated for almost two days. Used charcoal and hickory.
The marinade was : half a bottle of zesty Italian salad dressing, a package of beef marinade, and a bottle of Budweiser. We're eating it while I'm typing this. Very tasty, and moist. Ill upload a pic later.