Credit card is a big temptation. If you have one, do not bring it all the time. YOu will always be tempted to buy things that you actually do not need if you always bring your credit card. You are more prone to overspending. If you can live without using the credit card better cut it. And just stick to balanced spending and proper finance management to save money.
The said is actually true in respect to any payment card (debit, credit, or whatever). There seem to have been some studies that investigated into this issue, and when people didn't see their money literally disappear, they were more prone to a sort of discretionary spending...
So if you want to save more money get rid of any plastic that infiltrated into your life