Don't put emphasis on the word "perfect" - be flexible and maintain a sense of humor.

Don't procrastinate in your planning - hire all of your wedding professionals as soon as the date and place are set.

Don't hire your wedding professional until you have a working budget.

Don't hire the first professional you meet - check out a minimum of 3 for a proper comparison.

Don't hire professionals because they're the cheapest - you get what you pay for.

Don't assume anything! - get everything in writing.

Don't make decisions without consulting your mate - it's his or her wedding too!

Don't invite everyone you've ever known. - weddings are expensive.

Don't worry about everyone else's advise - -its YOUR wedding!

The do's 

Plan:
Give yourself plenty of time to plan. "Stress" means "strain" and "mental or physical tension", usually brought on by attempting to handle a multiple of tasks with a minimum of time.

A realistic budget and timetable are mandatory to keep you on track.

Organize  
all the pieces of the wedding.  A binder which will include separate tabs for wedding professionals, appointments, contracts, gown/ dress swatches etc..

Activate:
Prepare and follow a timetable of events, including appointments, deposits & payments, reviewing, contract terms, fittings, etc..

Coordinate:
Every aspect of the wedding day must be coordinated; Vendors and wedding party must be coordinated.

On the wedding day:
Pamper yourself
Spend quite time alone
Spend time with your parents
Eat something light
Relax - It's your day to enjoy
Do it your way - it's not a dress rehearsal