Bilingual baby?

Any of you ladies raising a bilingual baby(ies)? I am fluent in both spanish and english and my partner can also speak both languages but isnt fluent in spanish. Because of that, we find it easier to simply speak english 97% of the time. My oldest child is 19 months and getting to the point that shes starting to repeat a lot of the things she hears. I really want her and her brother to also be bilingual but im not sure how to go about it. Like i said, we speak very little spanish on a day to day basis and she already knows a lot of english words and some American sign language and i just dont know how to introduce spanish into the mix. Im looking for some personal experience from people who have taught their kids more than one language even if its not the ones i mentioned. Did you do both languages side by side or did you focus on one and then the other? TIA!