UTI and loosing your virginity?

I'm an 18 year old girl who's about to lose her virginity. I'm on the pill I've read all the stories about girls first time and possible bleeding and possible pain etc. And I know that when a girl has sex for the first time, she may also get a urinary tract infection. Is there anything I can do before hand that will lower my chances of getting one? I've heard going to the bathroom afterwords helps, and making sure he's bathed recently helps. is there anything else? also, if i do get one, should I make an appointment with my doctor immediately, or should i just take some vitamin C and cranberry pills and drink plenty of fluids and see if it clears up?