These are just some quick notes/suggestions for you.
1. It's fine and has a ghostly and eerie feel to it. Good use of lighting. I question the hair because it seems the hair is experiencing something to a degree the rest of the subject isn't.
2. The sharpness and lack of saturation work well with the subject. I think the purple/pink orb needs to be lifted up and to the left just a smidge based on the way her hand is flexing. My only real criticism is that the position of her torso doesn't quit support the gesture of her hand. The model looks like she's holding her hand back, instead of being in the process of hurling a pink orb at someone. It's like when you know people are using poses to fake action compared to photos of people who are actually doing the action.
3. I really like 3 and think it's the best piece. There's so much to be said with the archetype of the apple and it's connotation of poison, mischief, and seduction and her expression has that flirtatious appeal, like it's luring the viewer. The showering rose petals and her matching outfit and headpiece indicate that this is her domain, like a geisha of sorts. My only recommendation would be that brick wall. The brick wall just doesn't speak to anything else in the image. You have very nature oriented objects then WHAM...brick wall. I don't know how comfortable your skills in photoshop are, but I'd replace the wall with the trunk of a tree. Maybe it can be the tree she plucked the apple from and is leaning against it. I'd use a soft bokeh effect for the rest of the background, or you can keep it dark. Try experimenting, though the piece is strong enough as is.
If seduction is what you're going for, then consider making it more saturated. There are strong correlations with saturation/vibrancy and vitriol. The muted colors kind of work against that theme. Of course, if seduction was not your goal, then ignore this last suggestion.
4. Here the faded color works well to articulate softness and innocence. It also does give a heavenly feel to compliment the light coming from above.
5. This is the one I really wanted to comment on but decided I'd go ahead and critique the rest. Look, there are a lot of techniques people can use to help articulate different themes in their work. What I wanted to do was caution you with this last image. Whether you meant it to be or not, this last image looks instagrammed. I'm not commenting on whether that's a good thing or not because it's subjective. What I am telling you is that you need to be aware of this. You need to be aware of techniques that are easily acceptable to amateurs and widely used by inexperienced people trying to make their images look better. Otherwise your work may become disregarded like many of their work is. I'm not stating an opinion on instagram one way or another, but what I am saying is that there is a lot of criticism and jokes made at the expense of people taking a picture of their shoes, running it through instagram, and calling it art.
So just make sure the techniques you use serve to define your point of view as an artist. How does reducing saturation articulate my goal? What does a color gradient add to the image? What does reduced contrast convey to the viewer? These are questions that are important and rarely, if ever, should something be done "just because". This is what I wanted to say about pic 5 and now I want to discuss composition.
You're composition has been pretty good through most of these images but I feel it's a miss for picture 5. You have all of this space to use and yet you put the subject in the center. What did you put in the center? A pair of breasts. Now, that's fine and there are many pieces that focus on the sensuality, deviousness, and sexuality of female anatomy, but what I don't understand is the rest of the picture. How does her right hand or the hand with the apple relate to the chest? Why is her body leaning but she is centered? There seems to be a lot of things unintentionally competing for attention in this relatively simple picture.
Some constructive suggestions. If you intended to make sexuality a part of the piece, then you could have her holding the apple in both hands right above or below her breasts. You'd also want to crop the image or zoom in closer to help frame the subject better. If shes holds the apple with both hands, above her chest then you should still be able to fit in the lips which is another strong archetype of lusciousness and sexuality. You don't always have to use the rule of thirds but if you're going to break them by centering a subject, then make sure there is a reason for it. Normally when you center compose a subject it's because you want to put emphasis on it and normally it's used to suggest symmetry and structure. So, have her standing square, facing you to help reinforce the strong sense of rigid structure a centered aligned image indicates. Having an asymmetrical pose centered in an image rarely makes any sense. The few times it does is when it's more of a commentary of irony, social expectations, or to emphasize the wild abnormal nature of the subject. Your image doesn't speak to any of these things for me, so I just don't understand the point.
Overall, good job. Keep up the good work.