Do not use public Internet facilities and openo WiFi for Internet banking. Anyone can hack your account and withdraw money.
Do not provide photocopies of both sides of the credit card to anyone. The card verification value (CVV) which is required for online transactions is printed on the reverse of the card. Anyone can use the card for online purchases if they know the number.
Contact your bank if you did not get the SMS for credit/debit card transactions or if your mobile phone has been deactivated without your request.
Do not click on links in email seeking details of your account, they could be phishing emails from fraudsters. Most reputed companies will ask you to visit their website directly.
While using a credit card for making payments online, check if the website is secure. Notify your bank / credit card issue if you do not receive the monthly credit card statement on time. If a credit card is misplaced or lost, get it cancelled immediately.