How is the Nurse caring towards Juliet?

Although the Nurse isn't known for being particularly smart or well-spoken (she thinks she's wittier than she really is), her love for Juliet and devotion to her shine through in most scenes involving both characters.

For example, in Act 1, Scene 3, in a conversation with Juliet's mom, the Nurse rambles on and on about her memory of taking care of Juliet as a baby and a toddler. When you hear her retell this story, she sounds like a mother herself. Here she is, talking about how Juliet had learned to walk and how she'd bumped her head:

"And since that time it is eleven years,

For then she could stand alone. Nay, by the rood,

She could have run and waddled all about,

For even the day before, she broke her brow."

Throughout the first few acts, we see the Nurse talking to Juliet, listening to her, giving her advice, etc. We also notice how focused she is on Juliet's future, making sure she'll be well taken care of. Here's what she says in that same scene:

"Thou wast the prettiest babe that e'er I nursed.

An I might live to see thee married once,

I have my wish."

The Nurse means that Juliet was a beautiful baby, and that the Nurse's wish is to see her happily married.

Even when Juliet isn't present, the Nurse seems solicitous of her, eager to protect her honor and watch out for her interests. We see this particularly in Act 2, Scene 4, as the Nurse goes out to find Romeo to arrange the wedding for Juliet. Like a protective friend or mother, the Nurse warns Romeo:

"But first let me tell ye, if ye should lead her into a fool’s paradise, as they say, it were a very gross kind of behavior, as they say. For the gentlewoman is young, and therefore, if you should deal double with her, truly it were an ill thing to be offered to any gentlewoman, and very weak dealing."

She means that Romeo needs to treat Juliet right, not cheat on her or leave her or stop loving her. And when the Nurse later on realizes that Romeo has been banished, she even advises Juliet to try to get over it and marry the other guy, Paris, that Juliet's parents are setting her up with. Clearly she's still looking out for Juliet's best interest, trying to make sure she ends up in a safe, happy marriage that helps her keep a good reputation.