Experience is everything. You need to keep records of successful and unsuccessful transactions; and learn from them. Copy the successful ones. Avoid unsuccessful. Unsuccessful ones (fraud, chargeback) will tell you the way hacker/scammer works, and add prevention methods to your system.
For example, if you see too much fraud from a country that you see safe, add this country to your fraud monitoring/scoring system. If you see too much from from a phone number, add prefix and type of it. Examples dont stop.
Your fraud monitorin/scoring system is a live one.