Just learn to say “Jai Hind! Jai Jawaan! Jai Kisan! Jai Bohle ki!” and you’ll do just fine
Look up “Bald and Bankrupt” channel on YouTube - he has done a massive India series (and I find him entertaining).
“Delhi belly” is no joke so buy sealed water (though my worst case of it was “acquired” in Dubai).
Not sure I’d be going to India - especially Amritsar - right now with the tension and conflict looming with Pakistan...though might be the last chance to see it!!!