Build gothic furniture. Craft chairs with backs designed in the shape of narrow metal arches. Stain oak wood chests or furniture with dark -- or black -- colors. Add iron hinges and handles to chest lids and cabinet doors. Cut and stain plywood gothic arches for cabinet and bookshelf facades. Design medieval X-shaped chairs with puffy cushions and ornate trim. Purchase gothic decor books -- such as "Paint It Black -- A Guide to Gothic Homemaking" by Voltaire -- to give you additional ideas.
Add gothic accessories. Decorate mantels and shelves with displays of medieval swords, blades, chains and metal gloves. Hang lavish iron candelabras from ceilings or situate free-standing candle stands in corners. Hang plush tapestries from walls to add depth, texture and color to the room.
Hide modern furnishings. Place stereo systems inside cabinets with closing doors and/or build speaker stands out of dark, thick wood with openings in the frames to project sound and hide the speaker itself. Keep the room free of computers, television sets and DVD players. Display old fashioned books with tattered coverings -- but keep fresh purchases away from the room -- to maintain a realistic gothic feel.
Add lawn features. Make your backyard a faux cemetery -- fit with dark headstones. Position medieval-inspired lawn ornaments -- dragon sculptures, for instance -- on porches or in flower beds to spice up the gothic feel on the outside of the house.