A physical therapist who specializes in strengthening the pelvic floor muscles would definitely add one thing to this.

Before doing all that tightening breathe in to your stomach, not your chest and then tighten.

Now it does say it’s a beginning lesson. What I mention is what I got taught when I went to a physical therapist who only sees people for pelvic floor problems. She even brought in her boss (another PT) to go over the breathing instructions, more closely along with the sit to stand instructions, for more advanced pelvic floor exercising.