On the first turn of the game, it is not possible to discard. If there is absolutely nothing else to do, it is permissible in this situation to use a number 2 clue to save a 2 that is not on chop, but only if the other players can see that you had no other choice.
Saving Playable Cards when the Preceding Cards Are Not Promptable
Often times, a player will have two similar clued cards in their hand with the left-most being unplayable and the right-most being playable. In this situation, the other members of the team cannot use a Prompt to "get" the cards, since the left-most would misplay.
For example, in a 3-player game:
Red 1 is played on the stacks.
Earlier on in the game, Bob was given a 2 Save clue. Now, he has a playable red 2 on his slot 5 and an unplayable blue 2 on his slot 4.
Cathy has a red 3 on her chop.
If Alice clued the red 3 in Cathy's hand, Bob would be Prompted for slot 4, and blue 2 would misplay.
In this example, Cathy's red 3 is in danger of being discarded soon, so Alice is in a rough spot. From Save Principle, Alice is expected to not let the playable red 3 get discarded. But cluing the red 3 would cause Bob to misplay the valuable blue 2.
Players in this kind of situation will generally solve it in two ways: