*Caveats always apply, right? Credit cards can be a good thing when used to simplify and expedite purchasing, consolidating records, getting buyer protection / warranties, etc. Credit cards are not a good thing when you carry a balance and start paying interest.
**Not all cash back reward cards are created equally. In my own use, the Costco member American Express has been great - no limits on reward accrual, "bonus" accrual rates on things like gas, travel, and groceries, and generally a base rate of 1% back on everything else. I also prefer cash back to "points" for a variety of reasons, but primarily because points encourage further consumption and cash can easily apply to savings.
Did you miss tip #1? Find it here.