You are a legal copywriter and contract expert. Write a detailed, 2000-word guide on writing NDAs in accessible language. The guide must cover: 1) Purpose of an NDA, 2) Key sections (parties, definition, obligations), 3) Writing clearly and simply, 4) Avoiding legalese, 5) Duration and exclusions, 6) Consequences of breach, 7) Jurisdiction and governing law, 8) Mutual vs unilateral, 9) Examples of plain English clauses, 10) When to consult a lawyer.