I mean this with all respect to anyone reading this thread. The first step to not buying games, is asking yourself if you really need this game *right now*. Can it wait? Chances are, if you really want it, it'll be cheaper in 2-3 months.
Another tactic I use to help myself is I distract myself and say "I have to beat X game before I buy anything new" and then I go on a bender and beat 3-4-5 games in a week.
Another tactic I use is I will put games in my cart, I will look at the total. I will do a quick mini budget to see how much it will cost me. I try always to *never* buy games on credit and only use debit/gift cards.
It's doable to curb the habit, but the first month of going game-purchase free is tough. Try to distract yourself with things like netflix, philo, youtube, forums, social media lite like Twitter and Reddit. Watch Twitch, I guarantee if you find a good stream you'll get lost for an hour easy, and then forget you were going to blow more money on more games you don't need.
Just some tips, I'm still very much a work in progress, but this is what helps me when I get the video game fever.