[Alex KL-1]

+1 for voting about using at moderate brightness and color.
Or using at little less than maximum settings, but only for demonstrations.
Or maybe watching low bright programs like terror/horror movies (well, is easier with gamming).
I know that if one operates the CRT always below its maximum ratings, and with proper adjusted bright/contrast/color for most correct picture (considering the set in question) will results in a good life.

Make sure to measure the line voltage when using, avoiding using when is much higher than it's design (or reduce with a trafo or variac).

I believe that with such simple measures, will be a long life.

A extreme option is to make a "soft start" for the filament, to avoid the inrush current when powering on, but is not a common failure for a good CRT.