Keep your proofs in a folder ready for inspection. You goal is to assemble a collection of perfect proofs. You should include seven of the following eight types:
Proofs should be written in complete sentences. Mathematical expressions should be embedded in the text in a grammatically sensible way. Look at math texts to see how this is done.
Every step in a proof is or can be justified by a reason. Valid reasons include assumptions, definitions, and previously established results. The extent to which reasons are omitted and proofs abbreviated depends on the audience.
Observe the rules of good style extracted from Knuth, Larrabee, and Roberts's Mathematical Writing and quoted in the "Writing Mathematics" handout.