If you are a citizen of following countries, you can enter Latvia without a visa.
You should apply for D-type visa at the diplomatic or consular representation of Latvia. The following documents shall be submitted:
You should pay a visa application fee. It can be done with your payment card or by cash (depends on representative office) at representation of Latvia while submitting documents. Or you can pay the fee via bank transfer before submitting documents. In the latter case, you should add the proof of the payment to your application (e.g. a copy of the payment order).
Find more detailed information about Visa Requirements and Application Guidelines.