The Rosary is a wonderful way to develop devotion to Our Lady! Other devotions would be the brown scapular, first Saturdays, probably others I’m not thinking of…
As for books - my goodness, where do I start and how do I not overwhelm you! I’ll put it this way: go for what appeals to you. My brother likes Marian apparitions, so he used a book about those. I prefer the writings of saints, so I grew closer to her through them, by reading about how they understood her and honor her. My mother likes Father Mitch Pacwa, so naturally she has one of his books about Mary.
Honestly, the very best thing apart from the Rosary that helped me was spending time with a friend who has a strong Marian devotion. The way I refer to her as “Our Lady” is respectful and I hope loving, but it’s nothing to the love in this friend’s voice when he says “Our Mother Mary.” Even just a little thing like that impacted my own spiritual life.
Best of luck to you! May the dear Lord bless and keep you!