Especially useful with big firms (or if you're in difficult circumstances, just about anything): why do they need that money more than I do? would I give them that money as if they were a charity?
Browse stuff less often. As others have said, find displacement activities.
If possible, cut down on consumption of media with ads, lifestyle pages of newspapers, glam reality shows etc. Be more cynical when you do see advertising and advertorials, 10 best of product you can manage without anyway. Look at them as things that are trying to get money from you, either directly, or indirectly via sponsorship and ad revenue someone else is receiving (which for a while can increase annoyance versus previous passive consumption and acceptance of them.) Watch out for new things that might have this effect if you are susceptible.
Replace some of this with resources, blogs etc about saving money, minimalism etc. Try and change internal norms, e.g. feeling it's good that you've had something a long time and be proud of it, feeling better about yourself for cooking cheaper recipes, finding ways to adapt things for purposes for which you would once have bought something new, or managing without.
If you have any interest in environmental issues, think more about the resources used to produce and transport all these things that aren't really needed.
Consider important / emergency things you might need money for in the future and that you are wasting some of that on stuff you can manage without now.