yogafit seven principles of alignment
Establishing Base and Dynamic Tension
Our feet and hands establish a firm base for our poses, stacking our joints over each other and contract our muscles to create a feeling of stability.

Creating Core Stability
The muscles of the back and abdominal areas are used to create core stability and support.

Aligning the Spine
Core stability supports the spine, and our head always follows the movement of the spine. 

Softening and Aligning Knees
Kness should usually, unless directed otherwise, stay in line with the ankles and point directly out over the toes (not beyond them).  Keeping them soft, or imagining a small bend in them even when legs are otherise straight, helps prevent them from hyperextending.

Relaxing Shoulders Back and Down
This reduces tension in the neck and shoulders.  We can imagine they are slipping down into invisible pockets on our backs.

Hinging at the Hips
A straight back is essential as we think of our body as a natural pulley system of the ball and socket joint in the hips.

Shortening the Lever
The best example of this is our swan dive into standing forward bend.  We do this ith our arms out at a 'T', rather than overhead, to reduce the overall length of our bodies.  if our arms were over our heads, thinki about ho 'long' our bodies ould be and hat theat extra burdon does to our backs.
Some of these elements I specifically talked about in classes, and others were just inherent to the poses we did and they way they did them.  All of them are good basic elements to keep in mind, regardless of who you are practicing yoga with.