First of all I'm assuming you wanted her as the focus of your picture, if this was the case I would say a tighter shot would have been more appropriate. There's too much going on that draws the attention away from those lovely legs.
Second, the shot looks like she was trying to pose. If that's the case, next time from your perspective, don't be affraid to ask for her to twist and turn her body in a way that looks good on camera. I found when I started taking pictures of ladies, that the natural pose of a woman just doesn't look "good" on camera. Make sure she's willing, but keep in mind that she will be physically uncomfortable in order to get the best shot. Reassure though, that she will in turn end up looking like she should be on the cover of a mens magazine.
From experience I can tell you that getting a girl to "arch their back", and "point your toes", can be really embarrasing and somewhat make you look like a perv. And I shoot with friends of mine. If I was dating a girl I would have no problem making pics look sexier.
Seriously though, as long as your girl is comfortable being a model, you really have to ask for what you want. And let her know that a) she looks really hot b) It's just for a second.
Also some tricks when shooting with little to no equipment. Use mirrors, or even card board as a reflector for fill light for the shadows. Especially with harsh sunlight like that. Also use your flash if you can. It may sound odd using a flash in the daytime, but the end product will look remarkably better.
Other than that....have fun. I've had some of the greatest times with some of the girls that I've shot.