A (very stupid-seeming) trick that helped me is having my grocery list on my phone instead of on paper. I always have my phone on me, so I'm never going shopping again without a plan. Plus, always having my wants and needs and looking over them multiple times makes me think about them more. 'Do I really want frozen pizza, or was that an 'I'm so hungry' thought?'
Dr David Coleman suggests that when teenagers ask for expensive items, it's a crucial opportunity for parents to educate them about money management, saving, and making informed choices.