Weddingbee boards

I was pretty successful negotiating (but I am a lawyer ).  I think a lot of your power comes from where you live/are getting married and which service you are looking to negotiate. 

1. Venue - It can be hard to negotiate a venue down if you are looking to get married in a city, at a popular venue, or at a popular time of year (i.e. Saturday night in June or September).  If want to negotiate a venue, see if they can do a lower rate for a less popular day, time of day, or time of year.  Also see if they will give you a discount for booking within a certain time period of visiting (we saved $500 on our venue rental by agreeing to book or free our date within two weeks of touring the space).
2. Small Businesses - You probably have the most room to negotiate with vendor-owned businesses right now because the economy is still not great, and a lot of small business owners are having a hard time,  I definitely am not suggesting that you make it harder for small business owners to earn a living my asking them to provide services at no profit, but I have found that there is a lot of room to lower prices by just asking.  For example, our baker generally has a $1,000 minimum for orders.  I told her that we would have 90-100 people and did not want to spend more than $6-$7/person, then I just asked if she was willing to work with that budget.  She was.  So it never hurts to ask.  Caterers and photographers are especially flexible right now, I have noticed.
3. Compliments - You are much more likely to strike a good deal that both you and the vendor can feel good about if you find vendors you really like.  If you can tell a specific vendor why you would love to work with them, state your budget, and ask if they can work within that, you are more likely to hear good news than if you just try to negotiate for the sake of negotiating. 

Everyone has a budget (even if that budget is a million dollars), and vendors understand that.  If you are honest and respectful and put yourself out there by asking for a better price, I think you will be very pleasantly surprised by the outcome.  After all, the worst that can happen is that they can say no.

The one caution - I have never heard of anyone negotiating a really good deal on a dress (and I was not able to).  In terms of dresses, I think your best bet is to shop around (and maybe even look on preownedweddingdresses.com) and ask a salon you like to match another salon's price (most salons would rather have you buy your dress there and lose a bit of money than lose your business entirely).

GOOD LUCK!

P.S. I once saved 65% on a brand new leather sofa and love seat just by asking.  So remember, nothing is set in stone.  And mark ups are really ridiculous.

Make sure to read the contract very carefully. Where there is room for them to charge you extra, get it clarified, in writing.

Be polite and logical. They are not going to give it all away for free but hopefully will come to a win-win deal (they are in it to make money).

Good luck!