When it's time for a vacation, how far in advance do you start packing your bags?

I am leaving town next week for a few days and I have my suitcase sitting on the bed in my spare bedroom. I have already started to pack the minor stuff I need for my trip. Things that I have tons of and I won't miss a few pairs of. Things like socks.

Even though I am planning ahead, I always manage to leave something behind. I try to make a list of things I need to buy for my trip as well as what to pack. But again, it never fails. There is that one thing I forget.

How do you prepare for a trip? Have you come up with the perfect bullet proof plan? What is something you always leave behind? Tell us in the comment section below.