You are correct that some of us have time on our hands, or should be doing something else more important. Be that as it may, this site is definitely entertaining. It is also a place where opinions as much as they might sting, are honest. Some are offering useful help. It’s even free!
Pop-up-flash is not good or bad. It’s just a tool. A speedlight or speedlite depending on Nikon or Canon is also just a tool. The only complaints I have about pop-up-flash are the light is too close to the lens so red-eye is easier to achieve and the end of my lens tends to cast a shadow; and, that it is difficult to aim it in a different direction to the lens. Beyond that, I can control either one from the menu on my camera, so they are fairly similar at close quarters. The bigger light has more power which helps with longer lenses. With either light, control is the key.
I suspect the regulars here are more than a little familiar with skin tones.
Adding to what WCS said a few posts back … Usually it is good practice to light the backdrop separately. I’m outraged that they want $109 for that tarp, as a 5 X 7! As it is, it doesn’t do anything for me. I hope it is magical when properly lit and photographed. As lit in your photos, it looks like a drop-cloth that got dirty, wrinkled and worn. Not flattering, sorry. You could use white seamless and a blue gel on a flash or two to get a fairly solid blue background that would look better. You could put different gels on a couple of flashes to get mixed colours, too.
There is a spot on the water at upper left. Usually it is a good idea to remove that sort of thing with a cloning tool or a healing brush, depending on the editor you use and how well those tools work. Similarly, birds at a distance tend to look like sensor dirt so it is frequently best to remove them too.
Your sky is burned out. In this case it may be a good thing since it provides material to use when removing the tree growing out of her head.
Her arm is too bright. At her shirt, her left breast is too bright, actually her shirt is a bit bright and so is the post.
It could look like this (click the photo to see the full size version on Flickr):
Looking through some of your other photos, I see a need to level horizons, pay attention to focus, and watch for things creeping in from the edges of your frame.