Impulsive
The retail environment, online and in-store, is designed to maximise impulse spending. In shops, things are positioned so you see them as you make your way to what you actually came in for – online it's things like pop-up notifications telling you what other items customers have bought, or notifications that stock is low. Take time to consider whether you really need something. Stick to your original plan, and if you're still thinking about the other items a few days later, you might choose to go back to get them.
Pressured
Some people are better at standing up to pushy salespeople than others. If you're going into a retail environment where you think the pressure may be put on you, leave your wallet in the car. This gives you an easy out if you need time to think, and stops you from rushing into a decision you might regret.
Rushed
Sometimes it's not money that we're short of, but time. When you're in a hurry, you may just take the first option you see and not worry about the price. Shopping around almost always results in a better price, and you can often get your preferred retailer to match a better deal you find elsewhere, Comparison apps such as PriceSpy make it easier to check prices.