I agree with the idea that certain times of the day will lend themselves better for photographing landscapes - shadows/good light angle always help, but personally I tend to take photos when out walking and thus don't so much 'choose' the time I take photos.
If you are like me and just carry the camera about on walks here's what I try to do to make my landscape photos fantastic:
[I]Have a foreground/background feature. I find it often adds some more distance to the shot.
Get down low/up high. I can't remember who told me this (maybe the DPS blog) but I find that just kneeling on standing on something really can bring out a new angle/view of what would otherwise be a normal shot
If the sky has a few clouds try to get them in the shot instead of just blue skies. Entirely personal preference but I do like a few clouds in the sky to give it a little more life (especially if you have a lot of sky in the shot)
Some efforts of mine that I quite like...
