13. Make sure you're on the same page about your wedding plans before you start spending (or donating) any money.
Phoebe and Mike decided they didn't want a big wedding, so they donated the money they would've spent to charity. Then Phoebe decided she did want the wedding, and she asked for the money back. Think hard about what you actually want to do before you start throwing money around.
14. Don't assume your parents are paying.
Soon after Chandler proposed, Monica told her parents they'd need to make a "big withdrawal from the Monica wedding fund" soon. That's when she learned that the "wedding fund" is now called the "beach house." Her parents explained, "We just assumed if you got married after you turned 30, you'd pay for it yourself."
15. Figure out who's paying for what before the big day.
A tip for the groom's parents: don't offer to split the bill in half without knowing exactly what you're paying for. At Ross and Emily's rehearsal dinner, Ross's dad was hit with an itemized list of wedding expenses that included reasonable things, like flowers and liquor, followed by a bunch of upgrades to Emily's parents' house (where the reception took place) like the recarpeting of the first floor, the building of a new guest bath, landscaping, and the installation of a wine cellar and gazebo.
Related: Who Pays For What: The Traditional Breakdown