Every student is different. Before deciding how many, it is advisable to review your overall schedule for the year. This means weighting what are your interest after school -- Do you have part time job? Are you a one, two or three sport athlete? Are you active in clubs, cheer leading ? Do you have responsibilities at home right after school? All of these need to be weighted carefully and project ahead what your schedule will be like plus add in school assignments/ projects. AP course work is challenging and demanding and to select too many can put a student in a high risk situation -- becoming emotional drained, depressed, physical ill because of stress or have to drop course work because the student can not keep up. Trying to do so much just to impress an admission committee is a worth student's health ( physical or mental). Only you know your schedule, what you can handle, you know what is demanded of you by others. If you are a senior throw in completing applications, writing essays , going for interviews, taking any last minute college tour and the first ten weeks of schools are a pressure cooker for sure. So, be careful you schedule. i do not think there is a simple right or wrong number ( how many AP classes should I take), everyone is different and since that is so the number will be different. Plan carefully, talk with others who have taken the class, talk with the teacher of each AP you want to schedule and find out the requirements. Enjoy high school, there will never be another time like it in your life.