I can't stress strongly enough how easy Flexcoat syringes make mixing Etex, and all two part epoxies. Equal amounts by volume, per the instructions, plus thorough mixing, is the key. And no finger prints!
Flexcoat 3CC Color-Coded Syringes (Set of 2)
Dummy easy, thank goodness. Look up posts by Border Bass, and you'll see how to do it.
Basically, since the tips of the syringes are slightly tapered, you drill a snug hole in the caps, and leave the syringes in the bottles when you're not using them. Then, just hold the syringe tight in the cap, turn the bottle over, and pull out the plunger to get the correct amount.
Turn the bottle back over to the upright position, withdraw the syringe and squeeze the epoxy into a salsa cup, or other mixing container.
I mix the epoxy with a small, bare paper clip for about a minute, and then let it sit for another minute or two, until the big bubbles rise. I worry more about getting it mixed completely than about air bubbles, which can be dealt with. Rolling it around in the mixing container and blowing on it will help to break up the smaller bubbles, and brushing it on with a fine artists brush will also help break up the bubbles.