Originally Posted by
IanS
Shake the brush more before whipping the soap.
You are describing suds rather than lather, which happens when you start with too much wet. Once you have lather formed you can work water in a few drops at a time. You may want to practice this until you "break" the lather and it collapses into slime or suds again a few times until you get a feel for how much moisture you can/need to add before you start shaving.
Starting with suds is hard to recover from. If I spill a little too much water into my mug or forget to shake my brush, I toss the suds and start over.