Idea #10: If you don't "need" it, don't buy it.
Do not be drawn in by "sales" either. There are always sales. Seriously. Set up an email address that you use specifically for shopping. Subscribe to email alerts for all the stores you typically shop from. You will soon discover that there are always sales going. Check that account once or twice a week and clear it out. When you really do "need" something, go to your special shopping email account and do it up.
Idea #11: Avoid commercials on TV.
These just suck you in and keep certain products (usually the worst ones) in the forefront of your mind. Remember, these huge corporations have psychologists on staff whose sole job is to trick you into thinking their product is one you cannot live without. So just avoid them. How? Limit TV watching in general. This does not mean you have to avoid your favorite shows. Utilize Netflix, OnDemand, or DVR and with the last two options, FF through the commercials. If you are watching network TV with commercial breaks mute the commercials and get up and do something so you aren't looking at the screen either. Think of all the crap you can get done in those commercial breaks.