Waterfalls

So I picked up a ND filter with variable stops.. I used stop 8 on majority of my pictures. I've used a tripod ( not a cheap one but not a great one either ) and a 2 second timer. My photos seem to have some shakes in it as it appears not as clear. I need directions on how to get a crisper and less blurry ( not the water affect ) pictures. I am using a kit lens 18-135mm.. maybe I need a better lens?

Thanks for looking.

WF16 by Nam Ji, on Flickr

WF8 by Nam Ji, on Flickr

WF7 by Nam Ji, on Flickr

WF7_1 by Nam Ji, on Flickr

WF6 by Nam Ji, on Flickr

WF3 by Nam Ji, on Flickr

WF1_1 by Nam Ji, on Flickr

WF4 by Nam Ji, on Flickr

WF13 by Nam Ji, on Flickr

WF11 by Nam Ji, on Flickr