Trivet keeps the meat out of the liquid.
Correct amount of liquid is just to the bottom of the trivet.
Correct amount of heat will steam the liquid, rising to condense on the lid, driping down to self baste the meat.
You can also use vegtibles, cellery/carrots/onions, instead to lay the meat on.
I use beer for beef, 7-up for hams. sometimes creme of mushroom soop for the liquid for a briskit on the vegies.
Depending on depth & size of DO/CO, 1/2 to 3/4 hour before meat is done, add your vegitables to top of meat and add a little more top heat have everything in one CO.
Remember to start your dinner roll dough rising first, then 30 to 45 minutes before meat is done, pinch off dough, place in CO, set on coals and everything should be done at same time.