If you have done your research, great! If not here are a few things you need to know before heading to one of my favorite places in Italy!

No wheels. And when I mean there are no wheels anywhere in the downtown area of the floating city, I mean not even bicycles. There are no cars and no bikes, it is strictly for pedestrian use. Sure there are ways to drive to the town square but not any real access. So if you anticipate on renting a car and staying in the city center, I recommend to rethink or rebook.
24 hour water taxi tickets are a great idea! They are 20$ for 24 hours, but given this is the only way to get around the city, I recommend investing in a pass and paying close attention to when you may need to renew it.
The gondola rides are not worth it. For 30 minutes we paid 100 Euros, and that was split between 6 people. We almost fell over and tipped the boat, we were unable to move at all during the ride, and they did NOT serve us wine. I will say it may have been better if it were just us 2 and maybe not a group of us, but the price for that is outrageous to me. We also went during a busy time of night, so there is a possibility that it away not be as chaotic if you were to time it right.
Also, visiting the island of Burano is a MUST! it is such a quaint little town with eccentric houses painted bright colors. The locals are extremely nice, but everything closes around 6pm so make sure to get there early in the day before all the locals head home for italian family dinners!