This is actually really nice for a basis, although there is definitely room to improve (which isn't bad, everyone has room to improve). That said, I think I'll start with the wings?
You drew actual feathers, omg, and they're not all that badly placed (<- I am happy). You could do with a bit of research on wing structures, but I typically get way too lazy before I ever get to actual feathers and stop trying.
This isn't bad for feathers although it doesn't show the exact bone structure.
This is a bit better, it's an actual tutorial and there's a good deal to learn from it. The wings themselves structure-wise look a bit odd (curving rather than pointing, primaries are actually straight-ish) but
Lalala...
Other than that I'm kind of puzzled over a lack of variation in size from front to back which would indicate the wings extend out into the background (rather than just flat against the paper) while the critter's back is turned so it faces up (flank to viewer). This is sort of awkward, as I can see that the wing in the foreground is shorter but the wing in the back is actually... larger? Playing with vanishing points and solid objects might help a little. Also doing figure studies of models with variation in distance from the camera/viewer might be helpful as many creatures have similar anatomy (or at least the tricks can be applied. Evolutionary/biologically speaking, we all have the same bones just in different places. Not saying humans = dogs/cats/whales, but a human arm is very similar to a bird's wing if you imagine the fingers are the primary feathers). This is also more or less a prereq. for a lot of artist-type jobs, to be able to do model drawings/figure studies of human beings and get appropriate anatomy as it does WONDERS for helping you to understand how a body works and bends (again, comparative anatomy).
My last point on the wings (really the feathers) is the sudden change between appendage and body. I'm not sure if Bessie is scaled vs. feathered wings, or what, but dramatic changes in imaginary line places look.... odd in design? Typically colors blend into one another (typically, not all the time) and there might be transitional feathering/scaling/coloring/whatever to smooth wing into body. It'd be like if we had arms that were sticks, but then they suddenly hit the body and the body is not a stick. Also the arms are purple and the body is red. No fading, just a line between purple and red (I think my main beef is with the patterning not continuing all over the body :x Butbut, nrrr).
Uhmuhm, hinds quarters and tail. 1. I love the tail, fan-tails are good (especially for control in flighty things) and it's a very good start. A large part of being able to draw from the mind/make critters up is to know/understand the different functions of different body parts in animals. A tail-fan is used for steering. Might have made it a bit broader or extend up the tail (as your critter has a long beak I'm going to think it's a fisher? Like a pterodactyl?) as it looks like it might have a good deal of hard stops and turning in its lifestyle (a smaller tail does little to slow a creature down although can be used for very quick maneuvering. Again look at birds, their tails might be flat on their butts but they provide clues to how the creature flies/acts). Also, although I've done it a billion times to fit on paper and I'm not picking on it too bad, curling the tail back around is useless mid-flight and even possibly impossible. Like I said, not bothering it because I've done it too, fitting to my canvas, but it's something to think about. Planning and guidelines can be helpful to avoid uncomfortable squishing like that.
Hind legs I would encourage you to look at the hinds of wolves. It appears as though he has hinds similar to something that would walk on them only with a really flexy set of ankles. Studying bird feet and how their legs behave might be neat too, the toes look a shade clunky but not too bad. Also I'm assuming it has no fores? That or they're hidden by the wings - if it's the former that means he walks on his hinds when he's on the ground, you might give him stronger/longer legs (or possibly play with wing anatomy. Pterodactyls?
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Final point is the head. You know I'm going to say research, sorry I sound like a broken record :c Doing anatomical studies on skulls and drawing said skulls helped me a lot (
I actually did one for a fake lot of scaley-things I made) and learning how muscles attach can lead to better structuring. I would say that the eyes are a bit low and long? they're a bit large for the head and oddly placed (not much suggest the head is turned slightly to view the top more, although this might be a fair defense. In that case, biological things are typically symmetrical and there should be another side to his/her face?)
Over all, I suggest maybe trying less shading and doing more clean linework? Color can be added later on and cleaner linework allows you to see what you're doing (although dark marks, like on the wings, could be shaded). If you want to color everything in with your pencil you might try playing with light sources to make it a bit less flat or, or, try color pencil and color theory. Color lightly and try to play with color mixing and you can get some neat results (try using complimentary colors like red and green or yellow and purple in varying amounts to make shades and shadows rather than using black, it's beyooooootiful).
Other than that, it's a VERY good start. As I said, there are things that can be refine but it's very similar to how I started out. If you're serious about refining your skills and making a unique style for yourself, I suggest a good lot of anatomical research. As for your birdie-dragon, I like him/her (I know I referred to it mainly as a him, but I suppose it could be either. It has very dreamy eyes *3*). If you choose to keep building on this species I'd be happy to give you a red-line to help clarify a bit. If you are set on it you might even try doing references and working out specific quirks in the anatomy, etc. C: Good luck
Lalala... 
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