The central ray for PA is perpendicular to the midway between the ulnar and radial styloid processes
For lateral, it is perpendicular to the radial styloid process
FFD is 100cm. Direct beam (no Bucky).
Exposure factors: depends on individual x-ray system. It should be around 40-50kV and 1-2mAs.
You may split the cassette into 2 to accommodate both projections in 1 film. A 10x12 cassette is ideal.