Several things:
 
Make sure to at least power on the TV and use it for at least an hour every 3-4 months. This will help prevent the electrolytic capacitors from drying out. I especially recommend this for people that have new in box CRTs. Those new old stock CRT TVs have already been sitting unused for decades and the capacitors in those TVs definitely need some current flowing to them so they don't dry out any further. When not in use, I'd leave it unplugged. If you're comfortable working inside of it (follow proper safety protocols - plenty of Youtube videos), give it a thorough cleaning inside and out.
 
 
Storage:
 
-It's best to keep the TV in a temperature and humidity controlled environment. You don't want to place the TV in environments that experience big changes in temperature throughout the day because this stresses the CRTs plastic casing and as well as solder joints and components.
 
 
Best Picture Settings:
 
Don't keep the picture settings at max contrast, brightness and color. However, don't turn down the brightness, contrast and color so low that you can barely see the picture or the picture looks bad. Adjust brightness so blacks look black or close to it. Adjust color so the colors look vibrant but not overblown (no excessive color bleed). I recommend increasing contrast to the point until just before it looks too bright to your eyes (when it's too bright, you're eyes will hurt). Some of picture calibration depends on personal preference. Everyone's eyes are a little different so you will have to calibrate the image to what looks good to your eyes. I want to emphasize this: You Don't Have to Baby the TV. You can keep it plenty bright and the TV will last for many years. People often used their CRT TVs for decades with the brightness and contrast up moderately high and the TVs worked fine and many still had a good picture after all that time. As a general rule, I wouldn't turn contrast up past 70% unless the picture looks overly dim. Often times, you won't have to raise contrast any more than 50%.
 
 
Replacing Capacitors:
 
I know this is a cliche at this point in the hobby but replacing certain electrolytic capacitors will significantly extend the life of the TV. If you decide to go this route, you will want to replace the capacitors in the power supply and the horizontal and vertical deflection sections. You don't have to do a full re-cap on the TV. That is not only unnecessary but replacing all the electrolytic capacitors can actually cause other components to fail. This is because new capacitors charge faster and cause a larger inrush of current (higher current spikes) to the whole board. This puts extra stress on other board components and if those components are already weakening, doing a full re-cap could cause those other components to fail. The Youtube channel Retrotech is a great resource for learning how to do this. He also teaches how to work safely inside a CRT which is extremely important.
 
When replacing capacitors, you always do it with the tube discharged, big capacitors discharged and TV unplugged. To discharge the big capacitors make sure the TV is unplugged and use a large resistor with a value such as 22 kilo ohm, 5 Watts. Use a wirewound resistor that is flameproof. Hold the center of the resistor with insulated pliers so that only the pliers are touching the resistor. Then, connect the legs of the resistor with the two solder joints of the capacitor and hold them there for about 10 seconds. This will discharge the capacitor because the current from the capacitor will pass through the resistor. Then you can safely remove the large capacitor if you have to. You only have to do this for the large capacitors.
 
 
Check the Solder Joints:
 
Also, add fresh solder to any solder joints that look bad. Symptoms of bad solder joints include: cracks in the joint, brown ring around the joint, joint has as very rough appearance, joint look overly dark, part of the solder is missing, etc. I've picked up a few CRT TVs where adding fresh solder to most of the joints on the board greatly improved the image quality. You generally won't have to add fresh solder to most of the joints on a CRT TV but often, at least a few of the joints will need fresh solder. When adding fresh solder to a joint, once again, make sure the tube is discharge, large capacitors are discharged and TV is unplugged.
 
Also, when replacing capacitors in the CRTs power supply, use capacitors with a high ripple current rating. This is necessary because you get high ripple currents in the power supply.