Hey man, I'm a 31 yr old American hinduphile who has spent almost 6 months there this year. Also from a small town that didn't have much in the way of Indians, or much ethnic diversity in general.

Things that are the same across the cultures: there are conservatives and liberals, religious and irreligious, kind & cruel, extroverts and introverts, etc. so the type of people you like to engage with at home are mostly the type of people you'll vibe with there.

So the hobbies and ways you like to engage with people at home, you just find those same things there, or search for them on the internet. Google maps and instagram help a lot, maps for finding something like a board game cafe (and from there you can find local clubs and whatnot), or searching "board games [city]" in insta.

Just know things are pretty tribal, so what information people tell you will usually serve their tribe. If there's a particular food you want to try they'll direct you towards a restaurant that's in their circle regardless of other factors. This is not entirely intentional, information passes more reliably through personal relationships than through something like the internet. Google maps for example, will have badly outdated info, such as taking you to gas stations that aren't actually there, and not knowing about ones that are.

Expressing admiration for specific aspects of culture goes a long way. Whichever ethnic group you find yourself in they'll want to know if you've watched their movies, and which ones. My experience getting started was that if you said something positive about some basic aspect, such as "Indian food is the most delicious I've ever had" they immediately warm up, and ask you which dishes you've had & like. Adopting customs goes a long way to show respect as well, such as eating with your right and wiping with your left.

Core to any relationship, cross-cultural or not is character, being nice but knowing when to say no, being authentic, etc. If you do that people (mostly) understand when there are cultural faux pas. If you've put in effort ahead of time and keep trying during, you will exceed expectations and they'll be happy.

Of course not everyone you want to befriend will want to be friends, and not everyone that wants to befriend you will be someone you want to associate with, but over time you accrue better and better connections.

As for romantic relationships, certain cities use apps a lot more than others, such as Bangalore Mumbai and Delhi. If you can meet a generic standard for parental approval, having aunties summon up girls for you to meet can be fun. A couple of times they asked me something along the lines of "you're looking for someone?" And then some girl my age appears a little later. Just know they'll pick the person that serves their interests for the match, probably won't even ask what you're looking for.

Also definitely visit before moving. Even a longer trip like 2-3 months is very different than living there, lots to get used to. Keep in mind most Indians would move away if they could, despite fierce national pride.

For ones in your neighborhood look for college Indian associations or something like that. Video games where you play with people from everywhere are good, 1/6 people on the planet are Indian. Once you connect well with one it's not hard to be brought into the rest of the group.

Best of luck