How do you keep your tubes of glue such as E600 viable?

I stick the tips of my super glue in vasoline and it works great. No more wasted glue because it glued itself shut.

Oh. Be sure to screw cap back on over the tip. I usually wipe the vasoline off the top before the next use. Doesn't seem to effect the glues bonding property.

I feel your pain. I store my E6000 in a tightly sealed jar, I think that helps slow down the drying process. To open, more often than not, I use pliers around the cap to break the seal. Although a little more expensive, you might consider buying the smaller tubes.

clean the tips with whatever product the says to use for cleaning off your hands. Frequently vinegar for the silicone products.; then I put a suitable size nail in the opening; the head will fit inside the cap; Before you insert the nail, squeeze the tube from the sides, not the front/back; this will frequently cause it to suck in air and cleans out the tube of any residue there may be. Doesn't take much pressure and you can sometimes 'hear' it 'suck' the stuff back into tube.

Also, purchase the smallest amount needed for your project -- be a bit more expensive than the 'large' size, but it won't be as wasteful

I try to clean my glue tips before sticking the lid on to help and that works most of the time. I have also been told Vaseline will help it from sticking. A couple times when it has gotten stuck I have used a pliers to pull off the lid with luck, and I have also used hot water to warm and loosen the glue that is stuck under the cap.