My ATF yells out "keep doing what you're doing", when I tongue her clit at a particular area, but my tongue gets tired before she can come.  She then rubs herself off, while I catch my breath.

Anyway (good way) to practice without a real vagina?

Thxs in advance

You must be kidding, orbiter10,

But if you're not, maybe you can use these (see link). Otherwise, I urge you to get a bowl of jello or chocolate pudding and hold it up to your face. Let your tongue flicker around in there, since you need some form of resistance. Flicker until you can't move it anymore. Rest for a day or two and then resume.

At least it should taste good
The Love Goddess

I was trained by a harsh mistress who would not let me go until I had satisfied her many times.  Often I would have to go down on her for up to thirty minutes.  After a few years I got pretty good at it too.

There's no substitute for practice.

One down side however:

Recently I've had a series of gum surgeries and my periodontist was bedeviled by the strength of my tongue which instictively tried to interfer with his machinations.

This led to him having to use all kind of instruments to hold my tongue back while he operated much to the deteriment of my tongue and inner cheeks.

At one point in desperation he turned to me and asked, in all seriousness, what on earth did I ever do to develop such a strong tongue?

What could I say?

I just shurgged.  My mouth was full of cotton anyways.

"I was trained by a harsh mistress who would not let me go until I had satisfied her many times.  Often I would have to go down on her for up to thirty minutes."

Thirty minutes? How about an hour? And my Domme  had a riding crop if I showed any lack of effort or obedience to her commands.

But seriously, as a child I had a speech impediment. One exercise is to stick your tongue out as far as it will go and then curve it up and try to touch the tip of your nose with it. You do this several times in succession, two or three times a day, over a few years, and it will help you gain incredible dexterity and power with your tongue.

Then the next trick is to learn to breath thrugh the back of your head ...

While the link posted here is interesting, the exercises do not need to be so varied and complicated.

For a few years I have been regularly doing the following:
stick tongue out and move left to right, then in and out.  I do only for a few minutes, a few times a month.

You can do that while you are sitting at the computer.  I also do it at work.  (I'm waiting for a single gal to notice and ask.)

As a result, I can last 45-60 minutes without tiring.

Recent challenges:
1) 70 yr old lady: who said she never had more than one orgasm.  Gave her three orally.  "Wow" was the response.
2) 70+ yr old lady: as I was eating her she said she cannot always cum.  Gave her a rest then repeated "therapy".  She came and gushed.

Of course, in addition to stamina, technique is important.

I have references.
Signed,
The Talented Tongue

I love to please my partner.  I do not consider myself to "give" a woman Os.  I am but half of the partnership.  The best description I can give is I am the motor but she is the driver.  I am sensitive to her guidance & movements.  I have gotten tired but somehow managed to keep going.  
The reward...  a Fav lady breathlessly exclaimed "If you do that again, I'll have to pay you!"  I'd like to take her there again, but expect no compensation!  Well, not the cash kind anyway.  
I have no idea how to increase endurance except practice, practice, practice...
skb

Tongue muscles, like all others, would seem to respond favorably to being worked regularly. So eat as much pussy as you can...your endurance will get better!  Also, make it a mental goal to last long enough for her to achieve orgasm...you can do it!

Maybe try finding a way 2 get her off faster so you have some left in the tank for round 2 or licking and sucking other areas on her body.

Its clear that DATY is a skill that needs 2 be mastered and it changes from one woman to the next. However, there are some universal techniques like changing the angle, pressure, and motion you use.  Ive also found clit sucking or a gentle clit hold with your lips and tongue work like a charm. Ive found that 2 get my partners off faster and harder all the time. The trick is when 2 do it and how much pressure 2 use. The clit acts like a penis head so it gets engorged with blood and you can even feel the microvascular vessels plump if you use the suction technique. There's no mistaking her reaching that peak with this method. Alas ymmv especially if the familiarity isnt there with the provider.

HAPPY Diving!