I am 30 yrs old and extremely good in drawing and painting..so what are some good professions that I can choose which can ensure high slry?

Depends on the styles of your art. You can try becoming a storyboard artist for cartoons. You can become a comic book maker, or if you can do anime style, attempt to make Western manga (if you live in the West if not my apologies). You can further it and learn animating, you can make animations. Online comics could help you make a lot depending on how popular they are.

As a 30 year old you would know that no entrance position in any field is high salary.

To be successful and earn a lot of money with art you have to be extremely talented and extremely lucky. Good luck with that.

Unfortunately none. Art gets you no where in the business world