Someone is threatening to sue me, what should I do first?

Do not ignore it, but do not react hastily either. Read the letter carefully to identify the claim, the amount and any deadlines, and put the document in a safe place. Preserve all relevant records, including emails, messages and contracts, and avoid deleting anything, since destroying documents can seriously harm your position. Do not admit liability or make offers in emails or phone calls without advice. Seek legal advice quickly, and if a short response is needed, reply politely to acknowledge receipt and say you are reviewing the matter and will respond within a reasonable time. Check whether you have insurance that may respond to the claim, for example professional indemnity or public liability, and notify the insurer promptly because late notice can affect cover.