I have three tips.
(1) Along the lines of what Ziggy was saying, above: when I have several things in mind that I would like to do in the near future, and do not significantly prefer one to the other, I do the free things first.
Amazing how that lowers costs. You wouldn't think it would, but it does.
(2) An unrelated money-saving tip: In the summer, I keep the thermostat as warm as is comfortable, and wear nearly nothing and drink lots of ice water. In the winter I keep it as cool as is comfortable, and wear warm clothing and sit with a blanket on my lap.
What starts out being only a couple of degrees warmer or colder at first, ends up being a good ten degrees difference by the end of the season because the body acclimates as the season progresses.
To assist me in this, I have my programmable thermostat set with a default of 85 in the summer and 60 in the winter. If I do the manual override to, say, 70 in the winter, it will stay there for a couple of hours and then starts to drift colder. When I notice it is too cold, I manually raise it by just a degree or two.
(3) Another money-saving tip: choose your friends wisely. If your friends are not extravagant, you are less likely to spend money foolishly.