The audit (15 minutes)
Search for repeating amounts. Include the annuals: domains, cloud storage, prime-style memberships, app renewals.
Use weekly / use sometimes / forgot it existed. The third pile cancels today; the second pile gets a calendar date to re-justify.
The Subscription Cost calculator shows monthly, yearly and 5-year totals per item — the 5-year column is the persuasive one.
One service at a time, finish its shows, switch. $180 a year instead of $500+ for all-of-them-always.
Keep it from re-growing
Keep a note listing every subscription and its renewal date. New sign-up = new line, or it doesn't happen.
Set the cancellation reminder the minute you start the trial, titled with the price it becomes.
Annual billing discounts are real (often ~2 months free) — but only on services that survived a year of monthly billing first.