It is very important to calibrate the combination of lens and camera if you are serious about post-processing. Picture is worth a thousand words.
Click for a higher resolution file. Left is the default LR color profile. Right is the profile I created using ColorChecker Passport.
Here are some profiles for to download. YMMV.
Canon EOS 500D + Tamron 17-50mm
It goes without saying that the above profiles won't be as useful if your screen is not calibrated. I highly recommend Spyder products.