To begin the K1 visa process, first, ensure you meet the eligibility criteria, which typically include being a U.S. citizen, having a genuine intent to marry your foreign fiancé(e), and having physically met each other within the past two years. Next, complete Form I-129F, Petition for Alien Fiancé(e), and gather supporting documents such as proof of your relationship, financial capability, and legal status. Pay the required fees, and submit the petition to USCIS. Once approved, the case is forwarded to the National Visa Center (NVC), and your fiancé(e) will need to complete the visa application (Form DS-160) and attend a medical examination in their home country. After these steps, attend the K1 visa interview at the U.S. embassy or consulate, and if approved, your fiancé(e) will receive the visa to enter the U.S. Finally, upon arrival, you have 90 days to get married, after which your fiancé(e) can apply for adjustment of status to become a lawful permanent resident. Be sure to consult the USCIS website for the most up-to-date instructions and requirements.