Be specific
Instead of "handle my accounts," name the institution, type of account, and what you want done (e.g. "Close my checking account at First National; the statements are in the Financial folder"). The more concrete you are, the less guesswork your family faces during a stressful time.
Be kind
Your instructions may be read when someone is grieving. Use a calm, clear tone. It's okay to add a short personal note or to say why something matters to you. A sentence like "I chose this so you wouldn't have to wonder" can mean a lot.
Be thorough
Include contact names and numbers where relevant (attorney, accountant, bank). Mention where physical items are (safe, filing cabinet, with a relative). If something only applies in certain situations, say so. It's better to write a bit more than to leave gaps.
Tip: Review entries once a year and after major life changes. See Keeping Your Vault Updated for a simple schedule.