Here are Six tips to secure your online transactions -
1) SSL connection: This is most important and simple way to detect fraudulent activity. Just check the URL of webpage at transaction page. It must be stating with HTTPS instead of http.
2) Use Licensed antivirus: Most of the antivirus supports online web shield by which you can get trust score of website. So only use those sites which are having good score and don't contain malicious scripts.
3) Encryption of keystrokes: Cyber criminals can easily get your password using keylogging techniques. So use KeyScramber free tool to encrypt key strokes.
4) Avoid unsecured connections: Try to avoid use of unsecured connections like WiFi to secure your online payments.
5) Change your passwords frequently: It is good practice to change your account passwords frequently. I will also recommend to change pin of your credit or debit cards.
6) Make separate account for online shopping: Create separate bank account for online securing your transactions. Try to keep low balance in accounts to minimize risk of cyber attacks.