I think P7054964.jpg worked well. I like it best.
Your model needs a little retouch work, but mostly wardrobe and poses. Your first photo, P7135206.jpg, does not flatter her in any way! The “off the shoulder” top causes her to appear as though her right shoulder is very high and her left shoulder is abnormally low. If she is going to wear something off the shoulder, she should avoid shoulder straps. She should point her right toe more toward you and bend her right knee toward her left side. She should be about 10 feet from the wall if your lens opens to f/2.8. Add a few more feet if you have slower lenses or are stopping down for some reason.
What are you trying to say with P7135117.jpg? If you mask out her arm and crop tightly on head and shoulders, it might make a good head shot. That shirt is way too busy.
I took a picture of railway tracks the other day. Thinking about it, I have lots of photos of railway tracks. Most of them involve trains and/or stations. Read through the other posts here and you will see that a model waiting on the tracks, for the train, is considered a bad cliche. Perhaps you could cut her out of P7135277.jpg and paste her into another scene?
P7135111.jpg has good rim lighting thanks to the sun. There’s that shirt again. She has bumps on her forehead and something under her right eye. There is a bright white, burned out area just to our right of her head. There is dead grass hanging over the stones and some leaves creeping in from right of the frame. I don’t think the pose is helping. Her expression says “Please get this over with”.
What are you trying to say with P7135194.jpg? The concrete seems to curve off toward the edges. That may really be the case judging by the stone wall. Why do the stones have those yellow stains? What is that blue thing on the ground half way up the left edge of your frame? What is that other stuff on the ground just past her knee? Why that pose? It would be perfect for this kind of fixture:
Yep, that’s a washroom stall in Hong Kong, at Fong Ma Po. In 2006 it was new, and my flash turned on the tap at every sink!
Where was I? How about P7135290.jpg? Another not very flattering pose. She looks sad. The flower looks broken. The dead plant to her left adds that extra little touch of melancholy. Perhaps she is lamenting having her feet chopped off.
Summary of the constructive parts:
Flattering clothing, suitable colours, no words — unless you are photographing sports and the team name matters, no under-garment straps, no labels, … etc.
Watch your backgrounds, if you keep dead plants and garbage out of your frame, you don’t have to shop them out later. A few walls are really attractive, many are not. Get your model away from the background. If your model is closer to you than to the background, you have reasonable hope of shooting with a wide aperture and getting a nice background blur. An exception to blurring backgrounds is when you need context for an environmental portrait. If you are shooting in some exotic location, you may want the background to be sharp so people can tell where your subject was.
Shadows are your friends. Shadows give depth. Usually you don’t want deep and well defined shadows, though sometimes those are good too. No shadow gives “flat” lighting. Your photo ends up looking very two dimensional instead of three dimensional and your subject looks pasted in. I think you need to work on seeing light and shadow. Pay attention to the direction of light, sometimes side light can work well.
Fix bad skin, but don’t make it plastic. Pores are good, usually moles are left, eye bags and pimples/acne are faded or removed. Stray hairs may be left or removed depending. If they are over an eye, I usually remove them.
Try for good expressions. Describe a scene or plant a thought to get the expression you want.
Some subjects are natural models, they just seem to know how to stand and pose. Others need help. If your model is having trouble looking good while just standing there, provide something to do. Even if you are just doing head shots, pay attention to posture and hand position as it affects the shoulders.
Knowing how your camera works is important. Your exposures look alright. If you are going to do portraits, good, fast glass is helpful because you can get a shallow depth of field. Longer focal lengths help because they compress foreground/background, so noses look shorter. They also have shallower depth of field when your subject is close. Both on and off camera lighting can also help, depending on conditions.
Look through the posts here, you will see that we have seen much worse photos than yours. Keep shooting, keep tweaking. Think about the shot before taking it. Look at it again later and think about what you could improve next time.