For me, it has been a case by case basis. It seems though that what worked well for most viperids tended not to work well for most elapids, and vice versa. With most viperids, it was enough to just let them slide back out the way they went in. I didn't, however, cap the end, because they never got close enough to the open end to allow for a dangerous situation. With them, when I was finished doing whatever it was I was doing, I would lower the end the snake was sticking out of down into the enclosure, then gently either let the snake fall out, pull out, or pull it off of it myself. I never had any problems doing this with any of the viperids, be they rattlers, coppers, etc.
The elapids were always a different story entirely. They would often work their body into the tubes enough that they could get a grip on the inside, and they just would not slide back out the other end. In these cases, I most often would just let them crawl out the open end and retrieve the tube with hemos or tongs. Most elapids did this with very few being able to simply lift the tube away from them. They would always cling to the inside and go up with the tube, which could, as I'm sure you could imagine, make for a very dangerous situation indeed. Assuming that the tube is roomy enough to allow the entire snake's body to move through it without getting stuck, this may be the method you have to employ with them.
What snake is it specifically you are asking about? Knowing that might make it easier to give you tips in how to tube it safely.
-Chance
-----
Chance Duncan
2.2 Retics (1.0 Tiger Het, 1.0 Lavender, 0.1 Dark Lavender, 0.1 Normal Het)
1.1 Olive Pythons
1.1 Ball Pythons (Het Albino)
http://www.rivervalleysnakes.com