Mixing milk paint is a simple process using equal parts powder to water.  The mixing process takes about five minutes, using the following steps:

The mix is very simple:
1 part water to one part powder. 
Use whatever size scoop you want. 
Here I used a 1/4 cup.
Add water to the cup first.
Dry your scoop and add the same amount of powder to the water.
Gently stir in the powder, thoroughly mixing.
We did not add any “Anti Foam” to this paint, so you may see some bubbles. 
They will settle out more the longer the paint sits.

Real Milk Paint has a lot of pigment, but when going over an old finish for the first coat you will see some transparency. Give a second coat when the first coat is dry.

Here is a tip from Kelly of Furniture from the Barn:
I like to mix my paint two days ahead of time, then put it in the refrigerator. 
This makes Real Milk Paint very smooth and creamy.