Hi there. I've written about Venice several times in the past, these answers might interest you:

What factors made Venice an important center of trade?

How did the Republic of Venice last for a thousand years, and what brought about its downfall?

I think there's some overlap between those two answers, and I mostly focus on the Republic's early history, when it was most vulnerable to outside threats. If you have any additional questions do feel free to ask. I also wrote more banal and narrative answers about Venetian conflict resolution later on in the Republic's life, examining the state of affairs in the 16th century, and in the 18th century. I also wrote about the Republic's periodic conflicts with the Ottoman Empire here, as well as the War of the League of Cambrai, when the Republic came closest to being dominated by a foreign power.

Lastly, I'd add that it's important to keep in mind that the Venetians never considered themselves an empire in the traditional sense. I actually addressed that here.