I have a few simple things that I do, firstly whenever I decide I want to buy something I always wait a period of time after that initial decision, let's say 2 weeks, if after 2 weeks I still want it then I ask myself why I really need it and if it will improve my life, if the answer is yes then I'll buy it.
I like what you are doing because you still thinking if you need it or not before buying the things, its good that you know the worth of money, you will earn more money because you have a mind like that

But for me i have also the problem with this kind of situation, because sometimes if i think to buy a things like this i will buy it, no more days or weeks to think, if i like i will buy it, but when i started to have a family i change my attitude, before i buy things now im also thinking if its important, if not i will just buy something important for my family.