from what i saw in your post, there really isn't anything major involved in the post processing from above examples.
here is my little advise tho, post processing/photoshop isn't just about finding the right keys & controls in photoshop.
before you start, i think there is something fundmental missing here.
there is actually more to learn from the basic photography side point of view. first of all, a good understanding of colour and light is probably the most important, in your before and after comparison, why do think it looks better after editing?? is that because the saturation of colour, higher contrast, the lighting effect or simply the sharpness of the pic??
i never learnt photoshop through any proper institution or course, but i have spent a lot and a lot of time trying to get my photography basics right, from the most simple white balance to lighting senerio etc. and i believe thats the only way you can really master photoshop to help your photography because each photo requires different post editing, and only by understanding the photography, you will know what to look for in photoshop.
for example, your first pic, i can see the sky is a bit dul, so perheps increasing saturation on the sky by gradient tool and using mask, or simply the shadow/highlight adjustment, and adjust the actual saturation to bring out the colour of main object clothing, increase a little on contrast, fine tune the white balace, sharpen the image, there are at least 10 different ways you can do this, depending on editing skill, it can either be done in 2-3 steps within seconds or 10+ steps taking half an hour.
from my point of view, i always try to get the shot right before it even reaches the pc because i believe i am a photographer, if i do it the other way round by understanding photoshop steps or tutorial first and then taking the pic, i might as well become a graphic designer
anyway, here is my source for all adobe tutorial,
http://www.lynda.com
if you are dead serious, its worth to sign up on a monthly bases, i did it for 3 months, i can't say i am anywhere near a photoshop pro, but at least now i have a really good understanding of the programme, and i know where/what to look for when i need different tools for different purpose of editing to compensate the things i didn't/couldn't achieve in my nikon.