There could be pages written about o-line technique and what is taught. Windy hit on a lot of points, but he didn't hit them all (I'm sure he ran out of time and wanted to keep it simple)...
Here's other things I watch with pass pro technique...
Knee bend - Proper knee bend will help the lineman keep their balance, help leverage, support their base. If a lineman doesn't bend enough at the knee, they tend to bend at the waist and overextend themselves... again, makes them off balance.
Butt level - Somewhat related to knee bend is hip or butt level. Having a low ass lowers your center of gravity. Also having your butt in proper position will help your leg drive (especially in run blocking). A common technique taught to counter a bull rush from the defender is to sink your ass down low and drive your legs in hopes to cause a stalemate or even drive them back.
Staying Square- In pass pro it's important to stay square to the line of scrimmage until roughly the designed depth of the QB is reached (QB depth concern mostly applies to tackles, but it can apply to others). Staying square ensures you're not giving the rusher an open lane to attack the QB. Once that goal depth is reached, you can turn your body and push the rusher on by, giving that pocket shape. If you want to see an example of someone who is really shitty at this, watch Frank Omiyale vs. an edge rush. I'd say about 50% of the time he goes against an edge rush, he turns his body well before he reaches proper depth. This allows the end to take the corner on him much quicker than he would if Omiyale were square. A common reason linemen don't stay square is because they're simply beaten by quickness, or they don't have enough confidence in their own ability to stay with the rusher on the edge.

(someone wasn't in good position and turned too soon)
Active feet - A lineman will want to keep his feet chopping no matter what. Having your feet 'in concrete' is a good way to get juked or lose your balance. It's also a good way to lose a physical battle. You'll often see guys stop their feet on contact. Again, that makes you susceptible to various moves and is a good way to get pushed back into the QB. Usually lazy feet is more a product of conditioning than discipline. Though you'll see young guys do it when they're not tired... Webb would do this at times last season.
Quick set - meaning you want to see a lineman snap out of their stance and into proper pass pro position quickly. The quicker a lineman gets set, the better off they'll be. That's why in obvious pass situations, you'll often see some of the linemen not even bother putting their hand on the ground. Then they're pretty much in this set position from the start.

(closest I could find to a pass pro set in an image search)
I'm out of time. There's actually quite a bit more that could be talked about.
Keep in mind that the technique isn't necessarily the same across the board for all linemen, mainly the differences are in pass pro. Guards and centers have a little different approach in pass pro than tackles, etc.