just to start off your discussion..
I generally give a single remedy in a single dose, letting the person know the duration of the remedy from the table at the back of the Repertory.
Potency - I generally give a 30c, but will start lower if I know the person has pathology or has used a lot of medications over a long period.
In this case, I might use tissue salts or a 6c in an olfactory dose.(again a single remedy in a single dose)
Conversely, I will give 200c or higher if the case requires it, or I have exhausted the lower potency & the remedy has had some positive effect.