Dosage is dependent on the person and their symptoms, however I believe most doctors start at 37.5mg and go up in 37.5mg stages, and aim for about 150mg as the first-line therapeutic dose, this would match what Suzi says about her husband and also what happened to me.
But like Paula the dose it can go to 375mg. Just 37.5mg gave me horrible side effects and by the time I got to 150mg I was pretty much unable to do anything so it was not the medication for me.
Let us know how you get on. Don't be afraid to ask the doctor their opinion on doses.