In order to stop buying stuff you don’t need, you need to start off by understanding that it’s a habit that you’ve probably developed over the years, for whatever reason.
Ultimately, the purpose of a goal is to give you something to work towards and a sense of direction. In other words, ask yourself if that item will make you happier than reaching the goal you’ve set.
The thing about mailing lists is that all these companies you’ve shown interest in or supported before will keep flashing all their products at you and you’ll start thinking you need them.
Now this is a task for the brave. You’ll have to start by actually decluttering & separating your items based on what you actually use & what’s just been parking there for what feels like centuries.