There are a few different routes to take depending on time, finances, and personal inclination:
4) Accelerated BSN
Each has pros and cons.
If you aren't sure if nursing is the path you want to take or not LPN could be a good choice. There are typically limited pre-reqs, and the LPN program itself is usually less than 12 months in length, and quite afforable (under 10K for pre-reqs + program). You will want to research the scope of the LPN as it is not the same as an RN - would you be okay working in the lesser scope of practice? Also look at local job market, jobs for LPNs may be very limited. Getting experience and income would be the primary benefits of going this route, and if there are no jobs this could just delay getting where you actually want to be.
ADN, like the LPN cert has the advantage of usually being affordable. Typically 2 years in ADN program and 1-3 years of pre-reqs depending on what transfers from prior degree and how many classes you take at once while completing them. Depending on job market this could be a very sensible way to get into the RN workforce, but do your research! Some (most major metropolitan) areas are "BSN preferred" particularly for hospital jobs and an ADN could limit your job market - depending on what you want to do with it this may or may not matter to you.
BSN - apply to a traditional BSN program as a post-bacc student. Once you complete pre-reqs the actual RN coursework will take about 2 years to complete. The challenges are likely to be getting accepted - many programs have very limited spots for post-bacc students and cost, as tuition is bachelor's level cost but you won't qualify for finacial aid most likely since you already have another degree. On the flip side going this route would give you a BSN if that is the prefered level of education in your area, and the pace is slower than an ABSN meaning you could likely still work part-time while completing the program.
Accelerated BSN - these programs exists for students who have a prior bachelors degree and want to dive into a high intensity nursing program. Once you complete pre-reqs and are admitted these programs run through the nursing curriculum in 12-16 months. These programs can be great for someone who is a self-motivated learner who wants to limit time away from the workforce (though be forewarned it is almost impossible to work while in one of these programs) while completing a BSN. The intensity can be tough on some students and these programs usually do not come cheap, frequently despite their shorter duration they are just as if not more expensive than a traditional BSN program.
Some things to be mindful of as an international student:
1) Check the regulations around completing a nursing program as a international student. My understandings is that U.S. nursing programs
allow international students to enroll. However when I had looked at going abroad as a US citizen to study nursing there were a lot of requirements about being either a citizen or permanent resident of the country in order to apply and I ultimately decided it was substantially more expedeient and affordable to remain in the U.S. Double check that there are not residency or visa limitations around enrolling in nursing school as an international student coming to the U.S.
2) International students do not receive financial aid, and depending on visa status may not be eligible to work while completing studies - know if you can afford tuition and living expenses with out a source of income.
3) If you are planning to return to your home country to practice make sure that a nursing degree from the U.S. is accepted for liscensure and eligibility to work (and which specific degree, not all transfer to other countries well, typically traditional BSN is best bet). If you are planning to remain in the U.S. look into work visa requirements starting now - my understanding is that it can take a long time to find an employer willing to sponsor and there are long paperwork processing times involved. The more you know about the process and the time frame the better shape you'll be in.
4) If your prior degree is not from the U.S. completing pre-reqs and applying to BSN programs (either post-bacc or ABSN) may be more difficult depending on how your credits transfer.
EDIT: You may want to check out the international forums on this website for more information about being an international nursing student / worker in the U.S.