Probably the most noticable item on most of those shots is the white balance is off
are you always using auto WB? regardless make sure you shoot RAW and you can tweak the WB a little
also tied in with White balance is sometimes skin tones can benefit from just a very slight tweak of the magenta
when tweaking white balance (in lightroom this only needs to be as subtle as +2 from the base value)
the first shot the lady's skin looks very pasty and pale so i would suggest the following
I'll put some values in to try in light room other programs the values might differ
increase the whitebalance temperature to warm it all up a bit (not sure without the raw but maybe 5200 or there about)
add in a little magenta on the wb colour tone slider +2
in some cases bring up your exposure a bit much better exposing a bit more than trying to pull it up in post though
then increase contrast a little +10 then tweak up or down a bit to taste
increase clarity a little maybe try +20 and again tweak to taste
increase vibrance +10 and tweak it
Add a subtle tone curve to bring in a bit of punch into the midtones also some very minor adjustment to the
black level can really help especially if your blacks are looking a little grey
if you are shooting jpg you should be aiming to nail your white balance in camera grab one of these and set custom white balance for each scene
http://www.ebay.com.au/itm/58mm-White-Balance-Lens-Cap-Canon-EOS-450D-500D-50D-/250562087175?pt=AU_Cameras_Photographic_Accessories&hash=item3a56aa0907these are easier to use and carry than grey card and work really well