How to Write and Speak Correctly by Joseph Devlin is a classic guide focused on improving writing and speaking skills. Written in an accessible style, the book covers essential grammar, punctuation, and composition rules, while also offering advice on how to clearly express ideas in both written and spoken English. Devlin emphasizes simplicity, clarity, and the importance of mastering the fundamentals of language to communicate effectively. This guide is useful for students, professionals, and anyone looking to refine their communication abilities.