Check the numbers. Keep your receipts. Make sure the amount of your purchase is right and deduct that amount from your checkbook so no checks bounce. Protect your card from damage such as excessive heat or magnetic objects which could deactivate it. Know the limits.
Many issuers limit daily purchases and withdrawals.
That's good security but could leave you short if you're away and exceed that limit. Permission to reproduce for non-commercial purposes with this copyright notice is granted.