Never forget the importance of the colour you're mixing on top of, and it's temperature. The key to raising values in colour-harmonious style is establishing proper jumping off points.
When picking colours, max out your RGB slider values. You'll always be safe. You can tone down saturation/value with your brush opacity. It's the only way of mixing in photoshop without losing saturation, plus you make sure that your colour stays in key (I set my brush sensitivity to very low, so it's very hard for me to fully apply any colour I pick. As a consiquence, most colours I apply will have some of the under colour in them, which will them harmonize with it).
The more steps a task involves, the less likely you are to do it right now. Often the number of steps/time commitment of any given task takes priority over its importance, which is why we the young tend to get lost in the internet for hours at a time. Tabs is the worst invention. So, don't rack the disciprine: Have your sketchbook, pencil, eraser and sharpener out and open at all times. Have music playing if you need it to draw. Get rid of as many obstacles as you can, because you're only a split second away from deviantart.
Sorry 'bout the colours. Will try harder to calibrate.
So as you can see, for a long time i've been experimenting with using mostly a soft airbrush to start out my studies and only coming in with the hard round at the end. You don't commit to a drawing right away, you leave soft edges in areas out of focus and it looks very realistic/painterly. Then, after I started doing concepts, I realized that you can establish values and planes much quicker with the hard round, albeit it's harder to give the object polish and take it all the way to realism. The style of our game sort of forced me to commit to hard edges everywhere, because that's how textures work in 3D. (Though imagine if you could have soft edges in the same way your eye works!!!)
TLDR, a combination of the two is what I decided to pursue. You start off with the soft airbrush and lay in your values and colours, then search for the hardest edges that define your image and put them in with a hard round. Rinse, repeat: Establish the general values/colours with airbrush, tighten with hard round or texture brush.