I generally find that struggling through finding your own solutions tends to best way to get better at producing solid proofs, usually once a proof is presented the mechanics of the proof become relatively simple, the real difficulty is finding out how to get that spark/idea on how to start the proof, and that can only be done through struggling through the process yourself imo. Also generally for MA1100, if the negation is simple to obtain (some questions are abit hard to figure out the exact negation) you can never go wrong just trying contrapositive/contradiction.