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.
Yes its a good idea, because if you dont really need the thing why you should buy it,right? So before buying one thing make sure it will help you or you can use it for everyday use.