For me, best way to buy bitcoins will still be the same old school way. Buying USDT via P2P & converting those to bitcoin. This way, I hardly have to worry about tax as the amounts I deal in will usually be below 1 lakh so it's fine until & unless I get the deposits from verified sources. In P2P, usually regular merchants having offline shops make payments so that can easily be reported as friendly transcations to avoid tax.
The usual problem comes while selling though which includes bank account freezing even if it's from verified p2p traders and the reason is explained in my other thread,
Why bank freeze happens - Detailed version. People who don't want to face any of this issue will prefer selling directly to the exchanges but when we do the 30% is inevitable since FIU collects data from every exchange so it's a complete trap or just stuck with our paper money forever.