Based on that photo and the accompanying blog post, it seems like you're on the right track.
In my opinion, the two most significant components in a good portrait - cosplay or otherwise - are lighting and expression.
Your primary task as a portrait photographer is to find good light, put your subject in it, and take the picture. If you can't find good light, you make it yourself: use external flashes, reflectors, scrims, or some other light source.
Note that MORE light is not always the same as GOOD light. Direct midafternoon sunlight is very unforgiving, as it creates hard, deep shadows, and squinty faces. An overcast day and the "golden hour" shortly before sunset are both great times to shoot outdoors.
Study photographs you like, and study photographs you don't like. Analyze the light.
As you go about your daily life, observe light and shadow, how it falls on faces and objects, the depth and hardness of shadows, the colors of light from different sources.
2. Pose and expression.
This one will probably be easier for you than for many people, since you've got a willing model who wants to work with you to make good photos. There are plenty of guides and rules out there, but even the "rules" can take you only so far. A lot of it comes with practice, both on your part and hers. And, the same rules don't work for all the same people. Try new things, try a variety of facial expressions, some will work and some won't. Sometimes (often) the best-looking poses don't feel natural or comfortable. Digital images are free, you can always delete them, and you'll probably get a laugh out of reviewing them later.
After those top-two components, youve got all the other "stuff" that make up a good portrait:
3. Setting & composition
You can't always choose a perfect setting, but you often CAN get a little creative to get a decent use out of an imperfect setting. Look past the subject at the background - if there's clutter back there then it'll detract from the portrait.
This thread is a good read - it's specifically about a car but a lot of the fundamentals are the same: [url]http://photography-on-the.net/forum/showthread.php?t=536323[/url]
I'm calling this one out specifically after reviewing the images on your blog post. Consider your third and fourth photos of Cosplay Daughter, outside the house: Good outfit, cute model, pretty good poses, and oh by the way check out my trash can and lawnmower.
Compare them to the Maleficent photo (that you obviously like) at the top of your blog post. There's no grand setting there, it's just a couple of brick walls - but they don't detract or compete with the subject. (Okay, maybe the red bricks detract just a tiny bit, only because red bricks as a background are a little played-out)
Corollary: You don't always have to pose "with" or "on" something. You don't have to lean against an arbitrary tree, because then it changes from "Look at Cosplay Daughter", it becomes "Look at Cosplay Daughter and this tree."
4) Technical stuff.
Your camera will eventually become a bit of a limitation, I won't pretend that's not the case. However, an expensive camera doesn't always make the best photos. It seems like your little point-n-shoot is doing a decent job as long as you have decent lighting - the skin tones and exposure look good in the photos on the blog, surprisingly good for a 5-year-old point-n-shoot.
If you can consistently find (or make) good light. it'll continue to serve you reasonably well. In difficult lighting, it won't.
There are things that it won't do, such as work well with off-camera flashes, or give you that blurred-background look that you get from an expensive wide-aperture lens. So, eventually you'll want to upgrade, but not before you've eked out every last bit that your point-n-shoot can give you.
I don't do a whole lot of "photoshopping" or special effects. I'm not very good at it. Some people are, and that's their thing, and more power to 'em.
But even without heavy photoshopping, a little bit of editing can go a long way. I do most of my editing in Lightroom, which is pretty inexpensive compared to full-blown photoshop. Photoshop Elements is also affordable and can do a lot. GIMP is free and powerful, no idea how the learning curve is.
Find somewhere that the background isn't cluttered, go out an hour before sunset, face her toward the late-setting sun, and do some more portraits. Look past the subject, move her feet and move your feet (and stand on a stepstool or sit in the dirt) to frame her nicely with the background elements. Observe how the pleasing "golden hour" sun plays on her face and features. Run through a bunch of different poses and expressions, see what works and what doesn't.
Side note: If you look around and network just a bit in advance, you can often find very skilled hobbyists or semi-pros at a convention who will do a nice photoshoot for free, or almost-free, or in exchange for baked goods.