I used to use the "close them all the same amount" technique but discovered it was easier (at least for me) to close them each one at a time until everything was stabilized at the temp I wanted. I add hot water for the longer, lower temp cooks, but generally none at all for anything at 275°F and above. The top vent is always the last to be closed (for consistency and airflow).
As Larry/Ron have said, catch the temps on the way up, don't use so much charcoal in the chimney, and give it a bit more time to get to the temp you want. Hang in there, you'll get it right.
No Excuses BBQ
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