I tend to be overly zealous on budgeting, but I've found some people are horrified at keeping spreadsheets or categorizing items. So for those people, here is a simple way of perusing your purchases without writing everything down.
When shopping, separate your items between necessities such as fruit, vegetables, meat, milk etc. When you reach the cash out desk ask the cashier to subtotal after ringing up the non-essential items. These would be candy, non-nutritious items, treats etc. At the end of the month you can peruse how much you have spent and what could be cut back on.
For other items you might be keeping track off, clothing for example, simply highlight those items on receipts, using a different color for each category. Keep the receipts in an envelope for a month. At the end of the month you can add up the different categories and write them on the envelope. In a month or two you should be able to see a pattern and may be surprised at what you can cut back on.
For those who are prepared to set up a more detailed budget, see my previous posts on budgeting.
How to set up a budget