What is the best way to teach a toddler a second language?

What’s the best way to teach our toddler a second language? My husband and I are English speakers, he remembers a few French phrases from high-school, and I can hold a conversation in German. We have a few children’s books that are in English and Spanish, and I would love for my toddler to at least have a basic understanding, but I have no idea where to start. Everything I’ve read online is just to learn together, but there was no real advice, or personal experiences Has anyone else gone through this that wasn’t a bilingual family? What worked best for you?