Learn away from the score
Begin with an open-hand demonstration. Ask an experienced player to explain a choice before moving the card. Keep the pace slow enough that everyone can ask a question without losing their place.
Separate recognition from arithmetic
Practise identifying a possible combination before looking up a value. Next, verify that the reference actually allows it. Only then write a score. This makes it easier to see whether a mistake came from identifying cards or reading a table.
Explain a decision
Take turns stating what you believe is legal and why. If two explanations disagree, pause and consult the selected rules. Do not settle a rule question by a vote about who sounds more confident.
Finish with one observation
Write one thing you understood and one question you still have. Bring that question to the next session. Repeating a small exercise with attention is more useful than trying to memorise every exception in a single evening.