I use a half inch border around similar stamps of issue,
Increase that to include Postmarks or Cover printing if shown.
Primarily to keep a uniform display.
Cut so the stamp impression sits square to the cut.
Here is an Australian Cut square that fetched $600
in 2014, Phoenix Auctions Australia
This occurred from a collectors deep knowledge of his/her discipline, (to recognise the importance) and the scarcity of the item.
Postal Stationery collector February 2014 Vol 20 No 77