What kind of issues are you having, is it high levels of fraud, or customers not recognizing the charge on their card?
One of the best weapons in your toolkit is an extremely generous refund period. Since customers can request a chargeback anyway, you may as well spin it to your advantage and proclaim your wonderful 60-day Refund Policy. Always better to issue a refund than let it escalate to a chargeback fee.
If the problem is fraud, make sure you’re doing the usual things like blacklisting high fraud countries, checking that the IP matches the customers billing country, seeing if the IP is an anonymous proxy etc. And remember that none of these alone necessarily mean fraud - there’s lots of folks who buy things while travelling overseas, and an ‘anonymous proxy’ could be someone using a VPN. If you’re processing the cards yourself through a merchant account, you might want to consider integrating MaxMind’s minFraud product into your card screening process.
Most of all, be glad you didn’t get hit with thousands of chargebacks in a single week, like Candy Japan did recently when they got subjected to a testing attack by carders: