Are there any constraints I can use to properly choose the values for these parameters?
Two key constraints are the approach ellipsoid and the keep-out sphere. Most vehicles have additional constraints the vehicle designers place on the vehicle in the form of hold points.
The approach ellipsoid is an ellipsoid that is centered at the ISS center of mass and is 4 km long along the v-bar, and 2 km wide along the r-bar and h-bar. Most vehicles designed for ISS rendezvous do not plan a maneuver that would enter the approach ellipsoid unless given authority to proceed (ATP). A vehicle that enters the approach ellipsoid without ATP should abort. NASA and Roscosmos will look at the vehicle's flight software to ensure that these constraints are in place.
The keep-out sphere is a sphere centered at the ISS center of mass and has a diameter of 400 meters. A vehicle must not enter the keep-out sphere until give approval (ATP). Most vehicles stop relative motion at a point, (a "hold point") that is a bit outside of the keep-out sphere where they continue to hold relative position (within some deadband) until granted ATP. (They can also be commanded to abort or retreat, or the flight software can decide to abort or retreat at this hold point. Commands to abort or retreat are always in order.)
Most vehicles have an additional hold point well inside the keep-out sphere. From this inner hold point, ATP enables the vehicle to proceed to docking or berthing. A commanded or self-imposed retreat at this inner hold makes the vehicle go back to the hold point outside of the keep-out sphere. Once ATP has been grated at this inner hold point, a commanded or self-imposed retreat makes the vehicle retreat to that inner hold point. A commanded or self-imposed abort makes the vehicle not only exit the keep-out sphere but also exit the approach ellipsoid.
Some vehicles add yet another hold point that is well outside the keep-out sphere but is inside the approach ellipsoid. One key reason for this outer hold is that it enables a retreat from the hold point that is just outside the keep-out sphere to this further out hold point.