How can do you extend the life of your tubes?

Well tube amps should never be left on unattended. Too many fires for a tube amp to just sit runnning all day long with no one watching it.
Tube preamps on the other hand can be left on 24/7 (usually)
I leave my four tube VAC Standard preamp on 24/7
As i am listening to music all day every day..
If all I listened to was on weekends.. I would turn it off betwwen listening sessions.

I only turn my tube equipment on when I going to be listening. A standby switch is nice if you have one (I do on one of my amps) but I would still turn it completely off if I wasn't going to listen a for a long time like for a day or two.

I would not turn an amp back on (like if you were changing cables or ?) for at least 5 minutes and probably give it a half hour and I wouldn't do it that often.

Another factor in how long tubes last is how hard the designer has chosen to run them.

When you get a new set of tubes I am a firm believer in NOT running them 24/7 or close to that just to speed up the breakin. I think best, for sound and longevity, is to run them 3-4 hrs then let them cool completely (4-6) then start up again. Do that for just the first week or so.

onemug, I too wait to power up my amp again after a listening session. At least one hour, but I try not to power down until the music is over for the day. Cannot always do, of course, but that practice is in my listening choreography.

I was under the impression vacuum tubes were akin to light bulbs so they shouldn't be on all the time. I keep my tube gear turned off and only turn them on when needed. My warm-up time is similar to Pops.

One thing I'm trying to help prolong tube life are various tube coolers and dampers. I'm new to tubes so I'm not sure this stuff will help. On my preamp tubes I've got Herbie's tube dampers. On my power tubes I have Pearl PCF tube coolers. They look like heat sink jacket when put around the tubes. They supposedly help with the heat. I just started with them so don't know yet if they are truly helping. This will be a long term test.

Jedinite24, tubes are similar to light bulbs in that in rush current is their main enemy. You will notice that most light bulbs blow out when turning on a light, that's in rush current.

Tubes will last longer if you avoid turning them on/off. Certainly some previous advice is solid. Do not leave tube amps on 24/7 unattended, and you can use stand by circuitry if your tube equipment employs it.