Too Much Alcohol Ink, Overshooting the Color Too Dark
The best advice I can give you is to mix the ink with the hardener first, and then mix the tinted hardener with the epoxy. If you have epoxy that uses very little hardener (like &quot;add 10 drops of hardener to 100 grams of epoxy&quot;), then mix the ink with the epoxy before adding the hardener.
That has several advantages:

You can take all the time you want for the first step. Since epoxy and hardener aren't in contact yet, the epoxy won't start curing.
Stirring always traps air bubbles. You can remove the bubbles from the tinted hardener before you mix it with the epoxy.
The finished epoxy will have less color that what you mixed into the hardener.
If you really fumbled and added way too much ink to the hardener, you can try storing some of the tinted hardener in a secure container for a future project. Add more colorless hardener to your mixing cup until you got the color right.

The one big disadvantage is:

Once you mix the hardener with the epoxy, the color will change again. If it doesn't have enough color, you start adding ink again, with the risk of adding too much. But at least you'll have a feeling how much ink you'll need and if a drop might be too much and you want to use a toothpick to add the ink instead.