hey hey luv2travel
welcome to the forum, right place to be and learn about how many different answers you will get. where are you traveling from, USA Canada and how many people are you traveling with?
good idea to fly into venice for 3 days to get a taste of it. lots to see and do, walking along thru the canals, getting lost and finding you way out, it's fun don't get frustrated just laugh.
aussie and andrea have mentioned the shared water taxi from airport (venicelink.com/shuttle), best way to arrive in venice and worth it. keep the address/phone number of hotel you are staying at, it will take you as close to hotel as possible. we have used them 3 times. i also have whatsapp.com as many in europe use, download to your phone, text & calls are free.
we have used booking.com for hotels. don't know your budget in euros, just know that european rooms are smaller, any mobility issues stairs/steps to climb with luggage, not many elevators/lifts, shared bathrooms, read fine print carefully, cancellation policies book all refundable not knowing what will happen when italy opens, keep up on covid-19.
camacana.com you can make your own mask
withlocals.com/treviso charms: history, tiramisu & processco
gpsmycity.com/venice plan your walks to different areas/districts of venice
facebook.com/cocaeta makes crepes on the canal on fondementa cannareggio, just walking and roaming
ride a gondola, pick up in back canals (80E daytime) set price or you can email luckyluca6@hotmail. he's the singing gondolier, we loved it.
schezzini.it email alessandro, he does a cicchetti "bar crawl" wine history and small bites.
destination360.com/venice/cicchetti tour an old article but gives you info what it's all about, it's fun
isoladiburano.it take the vaporetto to the island of burano, things to do and curious things. my favorite island, maybe you can go to both murano and burano. taste the famous bussola cookies, the cute pastel houses of fisherman, watch your time to get back to venice
streaty.com food & market/ood & wine tours.
bacarojazz.it near rialto bridge. we had a meet up for happy hour with about 12 fellow greek isle cruisers from cruise critic. it was a fun place, they had so so many bras hanging all over, we brought a purple large size one, decorated with sequence and fufu lace, to hang up and leave our mark. we all had a good laugh
you'll be kept busy, see the rialto bridge and san marco square but walk away to the outer areas, sit at a cafe, have a drink, people watch. i sat right across train station on the grand canal at ristorante da nino with the "best" tiramisu and prosecco.
just some other options for you, you have time to research, make a folder for each place, what are must sees, if time sees, and no sees. check train schedules, use italian names for stations ( venice venezia santa lucia, florence firenze santa maria novella rome roma termini)
i'll gather a few more things and send you. you'll have a fun fun time, you'll have done your homework which helps, give yourself time to acclimate to new area, you can't see and do everything with cramming, breathe the italian air, slow down, don't just go go go. when you get lemons make lemoncello.