Out of the 12 tips Real Simple recommends for spending less, the most innovative is their tip for how to organize your shopping trips. They cleverly suggest that when you're shopping with the purpose of buying something that will inevitably be expensive (like a computer), you should select the smaller items first (like the software and other accessories).
The rationale is that after we buy something pricey, we're more likely to mindlessly buy more items that we don't need, because in comparison the amount seems insignificant. It reminds me of a common comment from those undergoing home renovations: Once you've spent thousands on new cabinets, it becomes difficult to evaluate the cost of things like knobs.
Because I'm not buying a new computer any time soon, I'll keep this money tip in mind the next time I'm shopping for things like a new coat or boots and underwear at the same time. Lingerie section, first!