Sorry to say, but the Bug-In Castle approach for the average home near a high density area is a lost cause. While it would be prudent to take every precaution you can to make access as difficult as possible (alarm system, heavy doors with reinforced frames, etc.) the truth is that given a determined enemy in a real SHTF scenario there is 0% chance of effectively defending the average home for very long. If you had a well armed troop, maybe. But alone, you will merely be stretching out the inevitable.
Truthfuly, if your within 10 miles of a major metropolitan area or traffic artery I would consider relocating to a safer local. Ideally a rural property with at least 10 acres and a home out of view from the road would be ideal.
Ideally I would build a home out of either full sized logs or stone (granite) with a full sized basement. Square log cabin design with an loft will be easiest to keep warm. Limit windows and doors on the main level. Out of sight from the road you can install metal bars on the windows, or better yet you can have a good welder fabricate 1/2 steel metal shutters with slits that can be closed shut in a pinch. You can also install a hardwood door with 1/2 steel plate sandwiched in between. I would also install a slate or metal roof to prevent being burned out.
At this point you can install a good wood burning stove (not a fireplace). You can use the stove to heat the home and cook. Solar panels, a good hand pump for well water, a vegetable garden, goats, chickens, rabbits, and enough food in the basement for 1 year and your all set.
Be sure to insulate the home well. 12 inch thick walls and plently of insulation in the ceiling will reduce your need for wood in the winter and keep your home cool in the summer. A light colored reflective roof will also keep the home cool, if you live in the a cooler climate black will absorb heat in the winter.
Off the beaten path you can set up some good perimeter defenses and early warning systems.