A busy opening hand can make every pair look important. The stronger first question is simpler: which cards can become a pure sequence without a Joker?
Mark natural runs
Look for two or more consecutive cards in the same suit. Middle cards usually connect in more directions than edge cards, but every route should be judged by the actual cards in your hand.
Do not spend the Joker too early
A Joker can support another sequence or a set later. It cannot turn an impure run into the pure sequence your hand still needs.
Recheck after every draw
A new card can strengthen one route and weaken the reason for holding another. Rebuild the hand deliberately instead of protecting an old plan by habit.