Hi there!
Gosh, I've been meaning to post here for awhile now but just haven't had a chance to sit down and write a proper critique.
I love how your characters have a good sense of motion to them or else a really nice curve so they aren't just standing completely straight. It makes it more interesting and dynamic that way, which is great!
I do think the anatomy could use some work though, and that would really help your art improve a lot!
Just going to use this picture as an example:
1) Wrists can be hard but you have to remember that there is a bone for the forearm and then the bones for the hand - they can't 'curve' so when you bend the wrist, it creases. The outside is straight lines, from the fore arm and then the back of the palm.
2) Similar to point number 1, you have to think about the fact there is a bone that keeps the arm straight for the most part and then add the curves of the muscles on top. Female arms tend to be slim but when you bend it the most prominent curves you'll get are the biceps and the flexers, just past the elbow as they bunch.
3) I've noticed quite a few people do this - they'll draw the clothes but sometimes fail to take into account what the body is doing beneath them. In this case her leg vanishes up into her skirt on a curve - but it doesn't quite marry up with the curve of her hip at the top of the skirt. Also pay attention to where the top of the thigh is and how it joins up to the hip area. I like to think of underwear for that bit - bikini bottoms definitely help you think of the leg movement in that area and how the leg bends and connects.
4) I'm not sure how to describe this bit but I get the impression there tend to be some curves where they aren't needed. You have to think about the anatomy and how it's working. Like I find the section right between the belt on her waist and the top of the skirt dipping inwards before it flares out odd and disjointed. You need to think about how the body parts interact, how things fold/crease or stretch around each other.
5) Lol, I didn't number it but this is for the legs and the groin area. I know it's covered by the skirt but again, you need to think of what the body is doing underneath to make sure things line up right. I feel that her lower leg that is stretched out starts a bit too far back and should be brought forward a bit.
Best kind of example I could think of with a leg coming forward so you can see the sort of line made from the thigh through to the shin.
Also - knees. They can be tricky. They don't have a point like your elbows when they bend.
This link is actually a pretty good tutorial on leg anatomy and the guy has an interesting way of doing the knees.
SO. That came out longer than I thought it would. Sorry ^^; I think you're doing good though and definitely try getting into the habit of looking up references for difficult poses and even trying the poses yourself to see how comfortable they are.