Do you want to start saving money?
The first tip is when you go to McDonald's. order the small size drink and fries. They are cheaper, sometimes considerably cheaper.
For instance, a small french fries is $1.00. Medium or large is anywhere from $1.60 to $2.20. Getting the small saves a buck, and is better for your heart. Learn to enjoy the smaller version.
Soft drinks are similar. Small size is a buck, and the bigger vats will cost 50 cents to a dollar more. If you really need more pop, go inside and help yourself to the free refill.
This assumes they don't have the drink special in your location where all the drinks cost are the same. I am a bit lost on that. What's the point? Who would order a small if the large is the same price? People with small hands? Small cupholders? It's either brilliant marketing or very dumb.
A word about combos. Do the math, and in a lot of cases you are better off ordering a small fry and soda rather than "saving" on a combo. Yes, you get more sugar and fat, if that's what you really want. But, you will still save money if you get the sandwich from the drive-through and drink a bottle from home, or God forbid, drink water.
The best answer when someone asks: "You want fries with that?"