The one tip that I think is really important but not always possible, is that the more time a bride has to look and shop the better. That way she is more likely to be able to take advantage of sales, and bargains. There are lots of things out there but it takes a lot of time to find things that you want or need at a reasonable price. Having a little more time helps this. Also networking with friends and co-workers helps a lot too. You never know what you will find in your buddies closet or in her sisters!
Lots of people have the little extras that help make your day special and are willing to allow you to borrow them or buy them in perfect condition for lots less than buying new! Wedding items are (usually) only used once and take virtually no abuse and can be reused a few times before they show their age or usage. It is fun too as a girlfriends ring bearers pillow could be used at your wedding and it could also be your "something borrowed" or your "something old"!Borrowing jewelry from an older relative who might have vintage costume jewelry is another way of saving money and again it can be the "something" in your wedding day. Lots of stuff like that can be passed down from generation to generation too. I carried my grandmothers handkerchief on my wedding day, and I still have the gloves that she wore on her wedding day! Some people don't want to store stuff like that, or don't have children with an interest in them so they would love to pass them on to someone who does.
Shop consignment stores! Again, you will find wedding items in perfect condition for less than you would at a bridal store. The selection isn't as big but you may find just the item you were looking for.