Do not leave packing until the day that you are leaving on a trip.
One of the things that I love about my wife is that she will start packing for a trip a couple days in advance. I however do not. I like to pack the last 10 minutes before we leave. I can't help it I obsess that if I pack in advance I will forget something. Of course I always forget something anyway, but my mental sanity depends on being able to pack the day of.
This habit annoys my wife. She will be packed and waiting to go while I am scrambling around the house looking for my Ipod. This is not to say that I am bad at packing or I am incapable of packing in advance, it is just hard on my OCD to do so.