#1 - Tell someone your plans; your maid of honor, your mom, the caterer, someone! Or, even better, write them down...with diagrams.
Leading up to and on the wedding day there will be many idle hands willing to work. And, despite your best intentions, you will NOT be available to guide them. I promise, you will be getting your hair done or deliberating over which shoes or fighting with your mom.
We need to know:
which chores need to get done - finish the favors, hang the twinkle lights, buy the ice
where things should go - how many chairs go around each table, where do we hide the computer
when everything is supposed to happen - is someone supposed to come out on the dance floor during your first dance to serenade you
and, most importantly, your priorities - what is the thing that must happen in order to make your day perfect and what can we let slide if we really run out of time?
Examples of bad planning I have witnessed:
the dirty bathroom with no toilet paper and no soap - a roll of paper towels sufficed
curtains being mistaken for tablecloths until 20 minutes before the guests arrived - good eye, Joanne!
the best man not being warned he should have a toast prepared - that one was just depressing.