To be the best at Uno Online you must pay attention to your opponents. Always keep in mind the number of cards they have in their hand and the cards they are playing. Save the +2 and +3 cards for emergencies. Don't play them too early, you may need them in case an opponent is going to run out of cards. Also, you should get rid of the high cards first. In case you lose the game, the high cards will give more points to the winner of the game. If you have the opportunity, change the color frequently. Use action cards wisely, they can change the course of a game even if you are losing. Cooperate with other players to prevent someone other than yourself from winning the game. And finally, drop cards strategically, so that you are always left with as much variety of colors and numbers as possible to be able to respond to any cards your opponents play.