1. Optimize the conditions
Make sure everyone (and that includes you) is well rested and well-fed to help bolster willpower. Be clear about expectations before you set out: Outline who and what you are shopping for, as well as what you aren’t going to buy.
2. No means no
If the answer is no—you don’t want to buy that glow-in-the-dark doodad—then you need to stick to your word. A bit of sympathy can soften the blow. It might help to let them look at the item for awhile. Then redirect like crazy.
3. Add it to the list
Keep a master wish list on you at all times. When they desperately “need” something, you can jot it down as a present idea for their next birthday or holiday. Bonus: They will feel their request has been heard.