I would take as many math and science courses as you can in highschool. You need microbiology and Chemistry as well as College algebra and statistics (depending on the school)
For my nursing school pre reqs I have college algebra, Speech, microbiology, chemistry, Psychology, Anatomy, physiology(sp)... I think i missed a few but that gives you a good idea. After those classes then you can apply for either a 2 year nursing program or a 4 year nursing program. If you high school offers you to take dual credits with a college for credit I encourage you to do it as it will give you some of the prereqs needed for nursing school.
Nursing varies on the payscale but they generally start out at least $20.00/hour and increases substantially with experience.
LPN's make quite a bit less and the schooling is not that much less. Also LPN's are not allowed to do as much as RN's and typically are not hired in hospitals.
If you are interested when you are looking for a job I would auggest getting a job as a CNA in a nursng home, where you will help residents with their skills of daily living. It will give you a good feel of the medical field.