Line Quality

I showed my some sketches for critique a year ago on an online forum there, a wise man told me:

LINE-WEIGHT MOTHERFUCKER- learn it!

Unfortunately I've never heeded this advice too well, as it's still something I struggle with. Some concepts I've been playing around with that give good results:

1. Keep a good grip- a 1.5" grip distance from the tip- esp. on outer contours.
-close in up to a .5" distance on details.
2. Slide into your strokes to keep a "thin on the edges-thick in the middle" sort of quality, dont hammer and stop from point to point.
3. Practice with brush pen.
4. I'm used to sketching with lines- in the case of improving line quality step back and instead sketch with dots, and render with lines. This is to say you figure out your proportions and everything with dots in a loose way, and you try to make all your lines high quality from the get go.