Useful vocabulary is organized by situations, not alphabetical order. For everyday communication, learn language for routines, plans, needs, opinions, and problems. For work, prioritize tasks, deadlines, ownership, progress, dependencies, decisions, feedback, and follow-up.
A word's usefulness also depends on tone. Need is direct and neutral; require can sound more formal or firm. Help is broad, while support or assist may fit professional contexts. Learn simple high-frequency language first, then add precise alternatives without making the message unnecessarily complicated.