Journal
A few words are enough to start.
Picture one person
Write as if you were talking to someone you know well. Use the name you actually call them. A familiar phrase can sound more like you than a polished opening ever could.
Choose one small thing
A memory you still smile about. Something you admire in them. A thank-you you have never quite put into words. Let one thought be enough for the first draft.
Leave space for your own voice
It is fine to be brief, to be funny, or to sound ordinary. Read the note aloud. If a sentence feels like something you would never say, try saying it more simply.
Keep practical notes separate
A personal letter and a household instruction have different jobs. Give each a clear title so you can find and review it later. Leave passwords and financial credentials out of the development build.
Return when you want to
Save your own copy and come back to it when your thoughts change. Preparing a message is a process, not a test. Check the recipient and schedule just as carefully as the words themselves.