Talk to her, but more importantly, let her talk. There isn't even too much skill to it. You just need a little practice. Women love to talk and you should embrace this. One way to encourage great conversation is by repeating the last word she said before she stopped talking.
'It makes me feel so relaxed...'
'Yeah, blah blah blah...'
Also relate to what she's saying. If she say sit makes her feel relaxed then say something about how you relax in the sunshine and how nice it is, and how it makes you feel chilled out. You just say what she is saying in a different way. Girls dig this.
Also, throw in some negatives, but always end on a positive. So say you love it, then say that you're scared of burning though. And then finish by saying that it's well worth it, and you should just use more suncream.
It really is that simple.
It also leads me on nicely to my second tip. Girls love to laugh. Having a good sense of humor is vital to picking up chicks. If you start seeing things from a positive perspective then you will become a funny guy. And don't be afraid to laugh at small things. Laugh along with her but never make her the butt of your jokes.
Stay talkative too. You'll quickly learn what makes her laugh and what doesn't. Use this knowledge to make her feel good. As soon as she feels good then she'd yours.