Make the frame 1/4" wider and 1" to 2" taller than the door. It is easier to shave the old door to fit the new frame for a good fit if necessary.

I generally measure from the top of the door to the top of the hinges for the location of hinge mortises on a new frame---which are then located from the inside top of the frame---- and add 1/16 for clearance between the top of the door and the frame.

Here again, shaving the door to fit is the easier procedure.

A story stick can be used here with good results, especially if the tape measure is old, loose, or a cheap one. Those three conditions often cause misalignment problems. Make the story stick by placing the stick---usually a thin piece of wood about as long as the door---2" by 1/2" or so. Align the top of the stick with the top of the door and mark the mortise locations.

Then tape the stick to the new jamb---allowing that 1/16" gap at the top and transfer the marks.