The 3 "Ps" are a must when preparing for a big event. Plan, Prepare, and Pack.
Since there will be multiple cars and multiple outfits we have to have everything prepicked and prepacked. The plan is only to have to move make-up and toiletries from one place to another. I have a bag to take for getting ready for the wedding the day of (as well as a mini bag holding my outfit for leaving the reception). I have a bag for the next day with my outfit to the cruise ship.
We are already packing for the honeymoon and I have everything that needs to go to my mom's house for before the rehearsal in another bag. I have seen other brides use this multiple bags and everything goes smoothly. I have also seen some "wing it" and things are forgotten and a mess.
A lot of people will have a emergency kit with them for bridal 911s, but the bride should have one too. I took an old coach case and filled it with the following "just in case" items:
2 sizes of band-aids
spare pair of earrings
However, no matter how much we try "we plan and God laughs". You have to be ready to roll with the punches.