This softball baserunning instructional video details proper run through and breakdown when running through first base. Emphasis is put on hitting the outside front corner of base (not top of base) which is the closest place to touch. The player should look toward the field after crossing the base and breaking down to find the ball.
Video also explains rule of making an attempt (feinting) toward second base and in what instances you can and cannot be tagged out.
Proper base turns are also demonstrated using a gradual swing out as opposed to a “question mark” when running to first base in order to get a straight path to second base. The last part of the video discusses leads.