If you are using wood chips, soak them first in water for at least 30 minutes so that they smoulder and smoke slowly, rather than flare up.
Using a Charcoal Basket
Dump the charcoal on one side of the charcoal grate. A charcoal basket holds the coals together in a compact bunch and slows down the burning process. Tap the edge of the basket with tongs about once an hour to knock the ashes through the basket holes.
Adding Wood Chips
Drain some wood chips and lay them right on the coals. Replenish them after the first hour of cooking, ideally when you replenish the coals.