How can I earn better being a cartoonist?

I suggest that you make Cartooning as a parallel career. Do not depend on it unless you acquire reputation in it.

You can learn techniques of drawing from an Institute, but creativity comes from within and on constant motivation from the right persons.First, cultivate the habit of vast reading and analysis and this takes quite an amount of time.A good cartoonist will be a scholar also.

Chetan, Cartoonist is an off-beat career which attracts a decent package due to exposure to social media's. You can take up in full-time and even in parttime

Yes you can earn you can also go for animation field