One thing to bear in mind is that there is a significant difference between Raw photo processing and working with jpegs!
With Raw (in Lightroom or even DPP) I'm starting with a "blank slate". I may choose a Profile, but more likely I just rund down the controls in the Basic tab until it comes out to meet my needs. But, those controls are all there to give us abilities to enhance our photos and, hopefully, to make improvements over what an out-of-camera jpeg would be!
Jpegs are different. The Raw data has been processed/converted, applying adjustments for various things that with Raw we would do ourselves. Because the Raw data has been processed/converted, there is a limit as to what adjustments are helpful, less is better!
I was, though, going over some old photos, and I had some that I had shot back in '03 with a jpeg-only camera, and I wanted to "share" some with a family member. I noticed that since I was shooting indoors at night, I used my built-in flash, and it showed in various shots, bright and shiny faces and such. Well, in Lightroom I was able to tone down Highlights and also use a touch of Vibrance, and those shots were improved! Realize that the LR Process 2012 (LR 4 and newer) are nice for this stuff!