Put future spending on a calendar
Pull out a calendar and look at your upcoming events and life changes. Will spending be necessary? Is so, then make a note of that and start building a list of future spending requirements.
This is somewhat different from a monthly budget because it looks a bit further out. This does two things: (1) allows you to prepare by saving for the spending requirement, and (2) it allows you time to shop around for the best price and lock in the lowest rates.