soft and out of focus images for D7000 on 18-105mm nikkor VR

the initial post request was asking for advice to improve my technique, I knew that I am doing something wrong and need to improve and this comes with practice!

so after a little study and try and error I did manage to improve a bit:

with little edit in lightroom as I did set the auto distortion in camera to on so I could not edit them in ViewNX2

above picture was shoot bright half sunny day and higher shutter speed and in AF-C 9pts.

Auto focus system works by subject contrast! and if there is bad lighting so the camera struggle to focus!!!! so other day when i was photographing the lighting was dim (gray cloudy day and shooting over snow). also 1/400 S is slow for my dog and the last which is the final important point is when to press the shutter full way so it take the picture, I was pressing it too quick or too late on the other pictures.

thank you all for comments and will keep practicing and please donot get offended or give hard comments I am just asking for a little help.

below is a shoot that I did take with my d3100 +35mm 1.8G 2 years ago for the same dog.

H.
http://www.flickr.com/photos/58485552@N05