Before choosing your cards, sort them by rank and then by color so you can choose the largest combination of cards to play.

I try to start with those of the lowest rank with the greatest number of cards 1st. But it is important to sort by color first in case you can find a large combination to play that way.

When responding to my opponent's move I sort by rank (or color) and again choose those of the lowest rank that still beat the opponent.

When your opponent reverts to playing single cards, avoid playing any single card that you can play later as a set. Otherwise you’ll degrade your hand by squandering a winning set you can play when it’s your round to begin.