1. You’ll never know if people are saying “yes” or “no”.
I’d heard about the famous Indian head wiggle, but had no idea how confusing it could be in practice. A wiggle can mean “yes”, but it can also mean “no”, “maybe”, “hello”, “I like you”, “okay”, “oh dear god why”, and many, many more things.
The key? When in doubt, wiggle it out. You’d be surprised how quickly Indians can figure out your awkwardly wiggly intentions, even when you don’t even know what they are.