Too much smoke. Billowing white smoke. The more the better. Close the exhaust some to let the smoke build. WRONG. I learned from a book using the soaked wood chips method and thought I knew what I was doing. This was 25 years ago and probably several thousand pounds of barbecued meat later I can admit this now.
BTW, I fuddled in the dark for years. Then I found the Brethren. My Que-ducation has increased exponentially since.