They're pretty good, especially if you've only just picked up spriting. If you don't mind, I'll toss out some crits for improvement!
The FE sprite: Well, it's...nice. My god, make the background transparent or extremely low saturation or something. It's making the sprite hard to view. Even without the background, a couple notes. If this is meant to be a genuine, true Fire Emblem style sprite, the outline needs to change a bit. Outlines of FE sprites are ALWAYS #282828. Other than that, there are simply a huge amount of very saturated colors. Too much saturation can burn the eyes a bit and, even worse, obscure the details of a piece.
The dragons: You nailed it - too much detail. That's one of the things that makes spriting an art, you need to be able to communicate detail without actually spriting it. The size boost in the female featherback helps a bit, but it's probably the wings and tail that try too hard there.
You have a good grip on lines. It's a good thing to know, lines aren't easy for me anymore. What is less great is shading and palette selection.
For shading, one thing to do right away is pick a lightsource. Your pieces here don't really have one. Pick where the light is coming from, and try to visualize how the shades fall on the dragons. You don't use much of the core pixel techniques, the most prominent of which are anti-aliasing(AA) and dithering. I wouldn't suggest dithering here, it can complicate the image, but AA is important. AA is a means of smoothing lines and keeping them from appearing too stark on an image. The thing you seem to be doing with shading here is simply defining more detail on the sprite, and it makes it look a bit messy at times.
<- not my image, but a great little tutorial from PixelJoint's tutorial thread.
The other thing that I'd work on would be the palettes. First, you use a LOT of colors. Most of the dragons, you don't need five shades of each color on a sprite of this size. That's because, as it stands, each thing just looks like one single color. Something that could definitely help with that as well would be adding more contrast, something there is little of, especially in the whites. Something else I'd recommend experimenting with is hue shifting. Hue shifting produces more visual interest I think, but it's something you need to be careful with, but I'd say try it out.
Here's a couple more of PixelJoint's tutorials:
Probably the best advice I can give if you really want to improve a lot would be to join a dedicated spriting site. There's The Spriter's Resource Community, but at least the PTers taking refuge there like to bite the head off of newcomers. The PixelJoint community is much more open to newbies, and there's a lot of really great guys there. I'd also recommend checking out how the masters do it at Pixelation(www.wayofthepixel.net), they're probably the best around.
Hope this helps, I'd love to see more! Always nice to have more spriters around.
EDIT: Gonna hijack your thread now. That Seatrench adult lineart was really speaking to me, so I spent an hour or so filling it in. Decided to go all bio-luminescent with the fins and stuff, I like how it turned out. If you're wondering how to implement some of those tutorial pieces, I have AA pretty obvious in the top left(the critter's back) on the curve, dithering all over but especially noticeable on the belly, and hue shifting going on from a cyan to a purple on the body as well as from a yellow to a slightly more reddish brown on the fins, though it's still quite yellow-y. There're 10 colors+transparency.
EDIT2: For great completeness:
Some crazy dithering on the left. I'll stop stealing your thread now.
Edited by Ego, 07 November 2011 - 05:39 PM.