Ukraine to America, tourist visa

[terrier]

Curious...I have a friend (of the opposite sex) interested in visiting the USA where I live. However, our relationship isn't exactly of the type where I would get a fiance visa. How does one go about getting a tourist or POSSIBLY student visa (though that's a lot less likely) from Ukraine to America? I hear so many conflicting stories from how it's nearly impossible especially for a younger single woman to how it's not that difficult if you go through a good travel agency. Any advice?

Thank you in advance!