I use standard kingsford charcoal with chunks of apple wood. I do not soak the wood as I thought that I saw somewhere that soaked wood isn't wet any deeper than the first 1mm around the circumference of the wood and this evaporates about 10 sec into the burn? Not sure.
About the cleanliness of the fire. My method is the minion method where I have about 3/4 of the fire area with unlit coal and then I dump in about 1/2 chimney of lit coal. Then i toss in wood. Throughout the process I'll add in unlit coal. I do not oversmoke throughput the process. I'll have soft smoke for the first 6 or so hours then no more smoke after.