2) Shortly before the sixth season starts get your girlfriend/boyfriend/dog/flatmate to downloaded seasons one through five and watch them all over a period of two weeks. Wander in occasionally, be confused at the sheer chaotic nonsense occurring on-screen and graciously allow them to explain things that Make No Sense to you.
3) When season 6 starts watch approximately two hours of it. You can accomplish this either by watching 5 minutes of each episode or watching complete episodes over the top of your laptop, not paying more than 5% attention. In either case you will easily take in more plot than you actually need to have a grip on.
4) Ensure that your girlfriend is hormonal. Or that you are hormonal. Or inject hormones into yourself. If you have no other option stick a slice of onion up your nose. Having something to help the massive levels of tearjerking that are going to be laid on is absolutely essential.
5) ABSOLUTELY DO NOT CARE ABOUT GETTING ANY EXPLANATION FOR WHAT IS GOING ON. It is a MAGIC ISLAND. If you want more explanation than that then you are watching the wrong show.