I would suggest that you first begin by tasting a small amount of
your pre-cum. Do that for about a week, getting used to pre-cum
first. By that time you will probably be licking as much as you can!

It's normally very sweet to the taste and easy to get used to. It
has none of that ammonia smell that sometimes can be associated
with cum.
Once you get used to pre-cum, then just take a very small amount
of cum on your finger and taste it. Later you will be able to take a
larger amount...and eventually lots!
ENJOY!!!
By-the-way....check out some of the threads abut "WHAT TO EAT AND
WHAT NOT TO EAT" inorder to make your pre-cum and cum tasty and
not bitter.