I'll use a three-tiered approach borrowed from Japanese Koryu to describe Bak Mei. It has levels of hyoho, tenouchi and waza; or, Strategy, Skill and Technique, thus moving from more abstract to more concrete.
On strategy level, Bak Mei aims to break the opponent's structure by forcefully disrupting an incoming attack and then entering close range. And then, dunno, maybe finish them?
On skill level, the line of attack is linear and almost straight up, with little sideways movement to enter (yet such movements are still found in forms); this is one distinguishing feature between Lung Ying and Bak Mei. Both hands are kept close to centerline, usually in a tiger claw posture (initial position for Mo Kiu, rubbing bridge). Shoulders are not squared, however, but in a very slight angle approximating 15 degrees. Power generation comes through sagittal flexion and extension of the spine. The training of forms aims to produce short power or inch power, which is called "scared power" in Bak Mei. This power can be utilised in several ways upon contact with incoming attacks, thus we do not aim for sustaining bridges for extended mounts of time. Main method of footwork is sliding, alternating steps occur only occasionally.
On a technique level, there are four main directions of technique (Sei Biu), sink-float-swallow-spit. There are different hand techniques that use different directions for different goals. Either hand hardly ever goes to a chamber either at the ribs or the waist, and in forms most attacks are executed with the right hand with the left hand mostly just clearing the way and making openings. Kicks only occur with the right leg (since stance is most of the time left leg ahead). Some (but not all) lineages use the classification of "Baat Sek" or "eight techniques" to deal with attacks, there's a video series on YouTube of them if you are interested.
