You can learn a lot about their tactics from this observation, which will also assist you in choosing which cards to keep. Keeping cards that could impede an opfantafeat loginponent's progress might be a good idea if you observe them routinely selecting cards from the discard pile that could finish a set or sequence. You can create a hand that not only advances your goals but also thwarts those of your opponents by choosing your cards proactively & paying attention to what they are doing.