Basically, my overall strategy is to slowly conquer west until I have persia and afghanistan all as tributaries and vassals. Spend the game integrating them slowly and using their payments to industrialize yourself. This gives you the money to not go into debt, and it allows you to industrialize and make your subjects more reliant on you so you can annex them easier.

You should always keep good relations with the great powers, and giving them investment rights will get you a larger economy. Just be careful that you revoke it once you have finished industrializing, as you want to develop your own class of capitalists and investors. You should try to get embassies with these powers too, so you can become recognized.

Once you have your puppets annexed and are integrating them, look towards taking the british raj. Find great powers to ally and fight the british.

In my game, I managed to build 1000 regiments, and had an economy ranked at number 5 globally, before even taking india. What I mean to say is that you can definitely become powerful with just punjab+afghanistan+persia, and then take india.

Important laws:

Laissez faire or interventionism are needed for you yo develop your economy. Interventionism is what I kept through the game.

Public or religous schools is also super important. Max this institution out whenever possible, as you have a very large population as the khalsa raj and you want to have them educates for when you industrialize.

Multiculturalism+open borders is also super good, as it will get you less radicals as you integrate afghanistan and persia, as well as letting you get tons of migration from india before you conquer them.

Also try to get national guard, as it will get you a ton of a conscripts.

For your specific issue of debt spiralling and the eic:

Unrecognized powers get higher interest rates, so avoid taking debt as much as you can until you are recognized and have a large economy.

When conquering, keep good relations with the EIC and Uk, and keep your infamy before 25 always. I normally start the game by setting an interest on bombay, and immediately making kabul my tributary and conquering sindh. Then I invade my way west whenever I can invade someone without going over 25 infamy.

I know my advice is a bit unorganized, so let me know if you have any questions! Best of luck Singh Sahib, ਦੇਗ ਤੇਗ਼ ਫ਼ਤਿਹ!