I Think a D50 should be putting better images then that....
1st one looks muddy, as in no contrast or anything to make it come out.
3rd one is a nice shot, its a bit cliche but it works sometimes. Your PP to it is terrible.
9th one should never be done again... that is the standard of cliche. Atleast move out of the way so you cant see yourself.
Work on your PP more, and I would say get in tighter on some of the dives.