PRACTICE COUNTING YOUR LOSERS.

There's a training version of bridge called "Minibridge" in which the bidding comes after the declaring partnership has been determined.  Seriously.  Here's how it works:

The players count their points (A=4, K=3, Q=2, J=1) and announce in turn their point count.

The partnership that together holds the most points will play the hand (in the case where both pairs hold 20 points, the cards should be re-dealt). The partner with the most points of the two will become the declarer.

The declarer's partner becomes the dummy and displays the dummy's cards at once.

Now declarer, with his side's resources known, decides on a suit and a contract. The rules recommend looking for an eight card fit to determine a trump suit, and the art of counting losers to state the contract remains useful.  As in the traditional game with bidding, Three No Trump is game, Four of a major is game, Five of a minor is game, and small and grand slams are as always.  Scoring is different.

There's an opportunity to work on your loser-counting skills at this Minibridge site.  The usual warnings apply, there's that off-side opponent void in the suit that you're trying to cash the ace and king, and sometimes an opponent is long in a suit and capable of running it, thereby yielding even more losers.

Have fun with it.