Always get it in writing

You see this mentioned on every planning site, in every magazine and every community of brides....Get everything in writing!

But, somehow that message doesn't seem to make it to every bride.  The wedding day arrives and the flowers are delivered and the bride is surprised when there are tiny yellow flowers in her centerpieces.  She hates yellow...however, she never put that in writing in the contract with the florist or even put it in an email.  The florist doesn't know that the bride hates yellow and so has to make changes onsite, or the venue manager or wedding planner has to remove the offending yellow stems.

It you absolutely want something a certain way, shape, size, color, etc, then put in writing with that vendor.  The same goes if you detest a song, flavor, or color.  Wedding vendors do their best to provide you an amazing day, but they aren't psychic.  So many misunderstandings can be avoided by giving specific lists or descriptions to your vendors.