Sufficient and necessary conditions do different jobs.
In “if P, then Q,” P is sufficient for Q and Q is necessary for P. The rule gives a consequence when P holds. It does not say that Q can happen only through P. Translating those roles carefully is more valuable than memorizing an arrow without its meaning.
A contrapositive preserves the original rule.
If P implies Q, then not-Q implies not-P. Reversing the arrow alone gives Q implies P, which the original rule does not establish. Negating both sides without reversing them does not establish a valid inference either.
Read “only if” and “unless” slowly.
The order of words is not always the order of the conditions. Identify what is required, then test your translation against the sentence. With an “unless” statement, first determine what must be true when the exception is absent; do not silently assume both directions.
Connect rules only where their conditions match.
A chain can justify a new consequence when one rule’s result supplies another rule’s condition. Check negations and quantifiers instead of treating similar-looking terms as interchangeable. An arrow chain should represent a defensible inference, not simply a pattern on the page.
Generate a drill, then explain the inference.
The member program can generate additional conditional-logic drills from its available ingredients. Use those variations to practice translation and valid inference. They are focused skill exercises, rather than an unlimited supply of unique full-length LSAT questions.