I have a lot of trouble getting landscapes to turn out right. Are there any suggestions/rules that I should follow? I do know that the horizon should not be in the center of the photo and that the sky should have some texture.

Here are what I consider my three best (They're still not good enough for me):

http://www.flickr.com/photos/21805952@N08/2104275673/
http://www.flickr.com/photos/21805952@N08/2105052112/
http://www.flickr.com/photos/21805952@N08/2104273869/
I am using a Cannon S3 IS
I adjusted them and this is what I got:
http://www.flickr.com/photos/21805952@N08/2105126254/
http://www.flickr.com/photos/21805952@N08/2105126134/
http://www.flickr.com/photos/21805952@N08/2104347959/

Here is another:
http://www.flickr.com/photos/21805952@N08/2105126102/

The compositions are a little weak, nothing that can't be fixed by more concerted efforts at framing... etc.

A pro landscape trick is to put something interesting in the immediate foreground.

The viewer's eye is forced to travel from the object to what is hopefully an interesting horizon.

This makes the picture more involving.

Hope this helps.