I've pasted fleur de lis wallpaper on the living room walls, and have fitted cornicing, which I've measured and sawed using a miniature mitre box (see the last picture for how I do this). Tomorrow I'm adding a picture rail and am cutting lollypop sticks to size before staining them in walnut for the floor. After they are fitted I can add a skirting board.
Skirting boards, cornice and picture/dado rails should always be mitred for a more realistic look. It's painstaking but worth it!