Hi Rich,
A Split ND filter or HDR technique can help when the scene has to much dynamic range
for your sensor.
HDR explained here:
http://www.luminous-landscape.com/tutorials/hdr.shtml" onclick="window.open(this.href);return false;
Try to use Raw, especially with photo's that have meaning or you may want to
get printed.
There is so much more information in Raw than Jpeg (4 times):
http://www.digital-photography-school.com/raw-vs-jpeg" onclick="window.open(this.href);return false;
Keep the rules of third's in mind when starting to take photos, place the point of interest
into the upper or lower, and left of right third of the picture, not in the middle.
Take you time to compose, don't shoot what you see immediately, but think about how
you can make scene even better and unique.
Lead the viewers eye to the main subject in your photo, using a ridge line, a river, a
stand of trees, stepping stones, a trail, a fence, a road for example.
Do not put the shoreline dead center thereby cutting a photo in half.
Always scout out a location ahead of time and go back during the golden hours when
the light is at it's best (sunrise-sunset).
Use you polarizer correctly for darkening your skies, not making them dark blue
or black. Also using it for cutting glare from reflecting objects like water. It can be
used in some instances to help you slow down the shutter speed to get that candy
effect on cascades and waterfalls.
Used incorrectly like in your first photo and second photo, it makes an unrealistic
banded blue sky, darkening the water to almost black, and you lost any shadow
detail on the limbs of the tree in the lake.
Also keep in mind that with a wide angle lenses it can give you vignetting on the edges
of your photo.
Also you have part of a branch in the last photo in the left upper corner. Always check
your view finder before pressing the shutter, and always recheck when processing.
Don't include objects that take away from you main subject, clutter is not good, and
distracts the viewers eye. For example the 4th photo has a rock at the lower left
corner which is to dark, too low (on the edge of the photo), and is distracting from the
main subject which is the peak in the background, and its reflection. Also the shoreline
is too centered, and there is to much sky, without clouds, and the lack of color in the
sky makes it uninteresting.
On the other hand in the 3rd photo there is not enough sky and to much water, the
rippling water adds nothing to the main subject, nor does the obtrusive rock at the
bottom of the photo.
Having a little more sky, a lot less water, and cropping it into a panorama would would
make it a stronger photo IMO.