I have 2 of those charcoal holders that form fit to the radius on the inside of my 22.5. I use about 3/4 chimney of charcoal split between the two holders. I use small chunks they tend to burn up fairly fast so if I want more smoke I open the lid flip the side of the grill open and add a small chunk to each side.
I buy wood chunks at Academy and I will still take an ax and cut them down to about 2in long then 1in by 1in.
Find I can regulate the amount of smoke I want this way.