If you're going to tip, tip early. It's standard to tip someone at the end of the job based on how well they did, but if you want the most from your wedding vendors then tip early in the day. Tips are never mandatory in the wedding industry but always appreciated. As a vendor, knowing a couple appreciates you enough to give you a tip stays in your mind all day. When your vendors know you already went above and beyond to tip, they will make sure to go above and beyond your expectations.
Encourage your vendors with kind words. As a photographer I've had brides who loved everything I did, and brides I was afraid could end my career. Who do you think ends up with better, more creative photos? Vendors get nervous too; a little positive affirmation goes a long way.
Listen to their professional advice. A good wedding professional has seen hundreds of weddings and wants what is best for you. Think long and hard before going against their advice.
Give Them Freedom. Artistic directions is good; micromanaging is bad. Great work is achieved by those with freedom to create. Something unique and extraordinary is never achieved by the over-direction from someone outside the field.
Feed Them. This was literally a post I just read from another photographer in my social media group: “The Wedding planner just told us there’s been a mix up ... no vendor meals for us, the videographers or the band. 🙁 We’ve been working since noon and are here another 3 hours.” This happens...a lot. All day vendors simply can't do their best work after eight physical hours with no food. This is usually the fault of the venue, and it's simply fixed by letting the venue know you expect your vendors to be fed so they have time to eat before dancing starts. (They often bring vendor plates as the first dance is starting.)
Treat your vendors like friends. Treat your vendors like friends instead of hired help and you will get the service of friends and not hired help.