Number 2, number 4, and number 9 of the suggestions in the blog post kindly submitted here are all well worthwhile. As my user profile discloses, I am an American native speaker of General American English (originally part of a monolingual household in a basically monolingual neighborhood of native-born Americans) who acquired various second languages. I have reached a high enough proficiency in Modern Standard Chinese to make my living for several years as a Chinese-English, English-Chinese interpreter and as a Chinese-English translator. I know maintain a bilingual household. I still enjoy language learning as a hobby, and my children attempt learning various human languages.
One old webpage I like with language-learning advice
Is your partner also 'an American native speaker of General American English'? I would be interested in learning more about households where both parents learned additional language(s) to raise their children bilingually.
One old webpage I like with language-learning advice
http://learninfreedom.org/languagebooks.html
lists some helpful books with a lot of research-based advice on learning new languages.