What are the most common mistakes startups make when entering the international remittance market?

I am going to assume the 'micro-transfer' is not a typo and that is what you are aiming for.

In my (brief) payments experience:

• Cost of transaction for the sender and the receiver - if the cost becomes a significant percentage of the over all micro-transfer, it will defeat the purpose. To the best of my knowledge, wire-transfers simply cannot compete with micro-transfers, and no one has been able to crack this yet.
• Minimize the exchange spread
• Settlement times
• Research into the beneficiary country to see if there is already a payment system that might be cheaper, more efficient than yours? one that you might be able to partner up with
• KYC/AML/OFAC/SAR reporting/checks