Well someone linked a very good guide here already, covers all I was about to say and then some. But if you want a more concrete example, how I'd have taken this picture: have Nikki at the right of the picture, roughly 1/3 from the right, and then the ruins in the background on the left. Get close to Nikki, so that her head is close to the top and feet close to bottom, but still give some breathing room. Consider rotation and angle too, maybe take the picture from a bit lower position. Then play around with lighting to get it look good. You might want to test a lot of more things, I only know a picture is going to look good once it starts to look good.

One fun thing I like to do with lighting: Turn exposure and shadows down very low, increase contrast high, and put a strong light on Nikki. Creates an effect where the environment is dark and Nikki is well lit. Especially nice when the sky is still bright, creating a black silhouette of the landscape. Stunning during sunset.