Have seen a lot of questions on carding online and what causes red flags. Below are screens from Authorize(.net) defaults. Should give some insight on how payments are declined and what sets off red flags. Keep in mind these are defaults but merchants can edit these however they like. There are a few other Fraud Filters you can configure but these are most important.
AVS:
https://imgur.com/sP0Jb3m
CCV:
https://imgur.com/qPZYhAQ