When carrying a credit or debit card around, it becomes very easy to overspend.
So the tip is to withdraw a set amount per week in cash that you plan on spending. Say you plan on spending $100 per week, then only withdraw that amount.
The only problem here is that you generally will finish your $100, and use a little bit more. So instead, withdraw $80 and set that as your spending limit. That way, if you finish your $80, you will use the remaining $20 on your card.
If you put fixed amounts in your head, you generally try your best to stick to that amount, which is why you should set a weekly limit slightly less than what you actually would like to spend.
The big upside, is that if you stick to your lesser budget, you will have more cash saved at the end of the day.