Go through the timeline of the day carefully and make sure there is someone who is managing it and telling people where to go or what to do next.
Going abroad on your honeymoon? Make sure your passports are up to date 6 months prior, and make appointments for any shots needed.
Make a list of everything you will need to bring with you on the big day. Gather everything in advance and put it in one spot so that you don't have to search for an essential item at the last minute.
Glass sailboat tea light candle holders in ocean blue that make perfect table decorations for a nautical or beach themed wedding, birthday party or rehearsal dinner.