I think it depends on your circumstances, and what is available to you. First, investigate the schools that are in your area for both, the LPN and RN programs. See what the requirements are. I don't know about where you live, but in my area (New York), the RN (and even LPN programs) are HIGHLY competitive, and limited in seats. You will need to earn a high GPA such as a 3.8-4.0 in the schools that have 300 applicants fighting for 40-60 seats in the RN programs. In that case (again, I am speaking on my area, only), they will give seats to the HIGHEST GPA. I have seen a friend of mine earn a 3.7 and did not make it in. The following semester, she did get accepted. Some have a limited amount of times to apply for candidacy (in my area, you can only apply at the community colleges twice-afterwards, you have to apply at a different community college).
Also, look at the areas you may be weak in, and try and polish those up. Find out if there are any entrance exams such as the National League of Nursing and if so, purchase the books and start studying. Some of my friends have gotten old GED books and studied from those. For example, I am weak in even the simplest of math, and took classes and got tutoring, so, when I sat for the entrance exam, I passed and did well. Good luck to you on your path to nursing!