It is really great to see that today's generation see Politics in a positive way. When I was a student, I always used to hear that Politics is not for Good people.
There are multiple ways in which a person can join National politics and I would like to mention a few based on my observation.
Narenda Modi style
Join a national party earlier in age like early 30s, work hard for the party, show good results and wait for the opportunities to come, prove yourself and grow to the top. This is a very traditional model of getting into politics
Rahul Gandhi style
If you are a son/daughter of a political family, then you can follow this approach. You can use your family name to get a ticket to contest elections and grow accordingly.
Nandan Nilekani style
He has proved himself as an executive in the Corporate industry (Infosys). Got an opportunity to work with Government on Aadhar. He was given Lok Sabha ticket by Congress in Bangalore
Shashi Tharoor style
Bureaucrats like IAS, IPS, IFS officers get a chance to get into politics because of their relationship with the politics and political parties. Even Army officers get a chance.
Sujana Chowdary style
A lot of businessmen get a chance in terms of ticket because of money, influence and experience.
There must be many more ways of getting into politics. You can choose a path that suits you best based on your background.