Unlike certain other bloggers, I'm going to skip the lengthy preamble and just dive right into the answer.
Just tip the people you would on any other day in your life. Tip your servers (though often caterers will have a built-in gratuity, but always clarify before signing your contract). Tip the bartenders. Tip your stylists. Tip anyone that helps with your bags. Tip delivery people doing set up. This is because the pricing for these services is often set up with tipping culture in mind (kind of like when you go to a restaurant, the labor costs aren't all present in the price listed on the menu).
For the rest of your vendors tipping is optional. Are you feeling generous? Did they go above and beyond with their service? Then a tip will certainly be appreciated.
There's a little more nuance when dealing with other vendors comes down to dealing with the business owner versus working with an employee or contractor. With a business owner, a thoughtful and positive review is often worth more than any tip but for a contractor, a good review is nice but they're not going to really benefit from it.
What are your plans on tipping for your wedding?
Ryan Richardson is a wedding and engagement photographer serving Boston and beyond; including Cape Cod Weddings, New England Weddings, Massachusetts Weddings and Rhode Island Weddings.