The great thing about tinder is that there's already knowledge of mutual interest. You don't have to think so hard; they right swiped you for a reason. You can always start by commenting on something you like about their profile; maybe you have a really cool shared interest; maybe they're doing something interesting in one/more of their pictures; maybe they're just really fucking attractive. Whatever it is, you don't have to be afraid to compliment them on it, because you already know that they're interested in you, so as long as you don't compliment them on something really strange ("I LOVE YOUR EARLOBES"), they're bound to be flattered.
As for what you actually want to get out of tinder, all I can say is that, by the end of the first date with anyone, be honest about what you want it to be. Tinder is overwhelmingly used as a hook-up app, but if that's not what you're looking for, there are still a lot of people who actually end up in a relationship (see: me and my girlfriend); you just have to keep matching, keep trying, and look for the right person. Or, if you're like me, go on tinder for shits and giggles (and/or ego boost), not really expecting to use it seriously, and be completely surprised by how amazing one match ends up being.
But seriously, tinder is one of the few situations in which you really don't have to worry, like, at all. Stay calm, message them, and if it doesn't work out, oh well; just keep getting new matches until it does. You have nothing to lose.
