Don't forget to eat. Many brides get caught up in all of the excitement (and nervousness) and forget to eat until the reception. Keep energy levels up throughout the day's events by making sure to eat a healthy, protein-packed breakfast or lunch.
Put makeup on before the dress. Don't risk getting foundation or mascara on the gown before the first photo is snapped! However, if the dress goes on overhead, then apply makeup after the dress ... Just be sure to cover shoulders with a large towel or wear a bathrobe over the gown.
Give an attendant a list of vendors' phone numbers. If for some reason a vendor is late (calm down: this rarely happens), have a bridesmaid make a quick phone call to remedy the situation.
Drink lots of water. Stay hydrated and in the vertical position (in other words, you'll be much less likely to pass out from being nervous.
Pack an "Emergency Dress-fix Kit." This should include some Shout Wipes, a needle or two, thread, some pins, an extra pair of pantyhose and Krazy Glue (in case the heel breaks off a shoe).
Have the maid of honor carry a few tissues. If tears fall during the ceremony, they can simply be wiped away (your groom will be glad it's not his jacket).
Check the weather report. For a hot or sunny day, take sunscreen and umbrellas for shade and pack a cooler full of ice and water in the trunk of the limousine. For a rainy day, pack lots of umbrellas and ponchos for the entire wedding party ... and take towels, a blow dryer and hairspray in case everyone ends up getting soaked.
Don't forget to breathe. When people are nervous, they tend to take quick, shallow breaths. If stress comes on strong, place a hand on the stomach and breathe deeply and slowly (stomach should rise and fall with each breath). This is helpful before walking down the aisle.
Find some alone time. Try to pick a time in the day to be alone even if just for a few minutes to reflect on everything that's going on and focus on the real reason the day is happening.
Remember: Almost every wedding day has a few glitches. Relax and take the minor problems in stride. At the end of the day it won't matter if the centerpieces had the wrong color roses, because you'll be married to the love of your life.