Vodka probably isn't the best place to start drinking, if you don't know your limits with alcohol and haven't really drunk before it's pretty easy to end up in a bad state quickly. If there's something with a lower alcohol percentage (beer, wine etc. There are websites with more info I'm sure), you could drink that instead.

If not, you could always try the vodka (half a shot with lots of mixer shouldn't mean you're on the floor throwing up)... but there'll be loads more opportunities to experiment with alcohol in the future so you need not rush.