After your 12th, You can do short term, certificate courses, graduation courses in arts and drama. Get some experience in theater side by side. You can build your acting skills with small competitions in college and add it later to your experience. You can also try modelling initially to get a boost in your career.You should have good memorization, communication skill and passion in acting. You can start participating in school, college events, participate in dramas, acting at state-National level.

Good Luck!