Masterbate at least once during the day you plan to have sex with her.
And dont ever and I mean ever have sex with a girl without a condom unless there is a very good chance you will marry her. I have heard on more than one occasion about girls saying stuff like they are allergic, or are begging becuase it feels better and then they are pregnant mysteriously.
Some girls will do this so you get them pregnant SOMEHOW becuase their birth control didnt work and then you attached to them. Dont do this, go and get some sheepskin condoms, they make them for 2 reasons, 1 becuase theya re thinner so you get more feeling and secondly becuase its for people who are allergic to latex.
Also if you are ever with another girl dont double wrap yourself with condoms, cause they will rub together and will break themselves, plus she might think your an idiot.