I have lurked for years, but could never add to the experts that posted before me until now.
In addition to the great tips above, when I need the highest temps possible (like for a sous vide sear) I break out a leaf blower and aim it at the side of the kettle, not the coals themselves. I get a swirling vortex of flame in less than 60 seconds. I would estimate the temps at around 900 degrees F, so keep your lid far off to the side. It can and will melt the plastic handle and lid holders if the lid is in the cradle at those temps.
In addition to the great tips above, when I need the highest temps possible (like for a sous vide sear) I break out a leaf blower and aim it at the side of the kettle, not the coals themselves. I get a swirling vortex of flame in less than 60 seconds. I would estimate the temps at around 900 degrees F, so keep your lid far off to the side. It can and will melt the plastic handle and lid holders if the lid is in the cradle at those temps.