Marrying someone from a foreign country is complicated by a variety of factors not faced by those marrying another U.S. citizen. While each relationship is different, these factors can include cultural, financial, immigration, linguistic, and emotional considerations. Before taking the big leap, you should thoroughly research and consider how these factors will affect you and your future spouse.
Consider the cultural background of the person you are marrying. Is that culture significantly different from your own? Are you very familiar with your future spouse's culture? Has your spouse spent much, or any, time in the U.S.? Are there other people from your spouse's culture living in your town or neighborhood? Is he prepared for the culture shock of moving to the U.S.? Would you be willing to live in her country if she felt uncomfortable here? These are the kinds of questions you need to be asking yourself.
Consider how well you know each other. If this is a whirlwind romance, or Internet-based relationship, do you really know each other well enough? If not, then consider taking more time before making such a serious decision. Find a way to spend more time together, or even live together.
Research the relevant immigration issues. Is your future spouse already living here on a visa or green card, or will you need to bring him here on a fiance visa? If the latter is the case, then how hard will it be for your future spouse to get a visa? This varies significantly depending on which country he is coming from. If you cannot find all the answers you need, you might be well advised to consult with an immigration lawyer.
What is your fiance's financial situation? Will he be able to work here? If not, can you afford to support him until he can? This is not just a practical concern for yourself, but if you must support him, then you should be prepared to demonstrate that to the government in order for your future spouse to get a visa. You should also be clear on whether your future spouse expects you to assist financially in bringing over other members of his family. This is also often a point of contention.
Consider your linguistic compatibility with your fiance. Does at least one of you speak the other's language well? Would you be willing to learn her language? Will she be willing to learn English? This is both a practical and a cultural issue. The inability to effectively communicate with one another can seriously harm your relationship. Additionally, if you were to learn your fiance's language, then she would feel more comfortable with you, and it would be easier for you to relate with her family. Always remember that it can be a very traumatic experience to be uprooted to another country.
Consider if there are any religious issues that separate you and your future spouse. While this does not have to be a problem, if you do not discuss your differences openly, then this could create serious difficulties later on, especially when it comes to how your children will be raised.