Get the right Exterior doors they should be fiber glass, solid wood, solid wood core (a layer of veneer over solid wood), or metal. Hollow doors are merely sheets of veneer over a cardboard core and can be broken with ease. Make sure metal doors are reinforced inside, and have what is called a lock block. Otherwise, they can be bent out of the frame using a car jack.
Lock your doors. In a significant percentage of burglaries, the criminal enters the victim's home through an unlocked door. Even the strongest Pick a Lock in the world are useless if you don't use them. Lock all exterior doors whenever you go out--even if you'll just be gone a few minutes--and also while you're at home, particularly at night.
Install deadbolt locks. With the exception of sliding doors, all exterior doors should have a deadbolt lock in addition to the lock built into the doorknob. The deadbolt should be high quality (grade 1 or 2, solid metal with no exposed screws on the exterior), with a throw bolt (the bolt that comes out of the door) at least 1 inch long. The lock should be properly installed. Many homes have lower quality deadbolts or throw bolts less than 1 inch. These must be replaced.
Install a dead-lock. Adding an additional lock will provide extra security when you are home. The dead-lock, sometimes called an 'exit-only deadbolt' is a deadbolt that does not have an external key. It is clearly visible on the door from the outside, but cannot be broken into without destroying the door, frame or lock itself. While this security won't help directly when you aren't home, the visibility may discourage an intruder from trying the door.
Locking the door with a key, Install cylinder guards around the lock cylinders (the part where you insert the key).''' Burglars can sometimes remove or damage lock cylinders by hammering, wrenching, or prying. Protect these with metal guard plates or protective rings on both sides of the door. Install guard plates with round-head carriage bolts to prevent them from being unscrewed. Free-spinning rings around the cylinders will prevent the use of a pipe wrench to twist out the cylinder. Many locks come with these already, but if yours doesn't, you can purchase them.
Replace flimsy strike plates. The strike plate is the metal plate that surrounds the lockset (the hole in the door frame where the lock bolt enters). All exterior doors should have heavy-duty metal security strike plates secured by four 3-inch screws. Many homes are built with lower quality strike plates or have strike plates that are secured with short screws that just attach to the door jamb, not the underlying stud.
Secure exposed hinges. Hinges should be on the inside of the door. If yours are not, rehang the door or secure the exposed hinges with non-removable pins. You can do this by removing at least the two center screws of the hinge (on each side) and replacing them with non-removable hinge pins (you can get these at the hardware store) or double-headed masonry nails. Even hinges that are not exposed should be secured to the frame with 3-inch screws.
Fortify your frame. Even with a strong door and quality, properly-installed locks, a burglar may be able to gain entry by breaking or prying the door frame. Most door frame moldings are simply tacked to the wall, and so a crowbar or a solid kick can easily separate the frame from the wall. Secure your door frames to the walls by installing several 3-inch screws along the frame and doorstop. The screws should reach the wall stud.
Peeping through a peephole, Install viewers. '''Viewers, also called ''peep holes'' allow you to see who is on the other side of the door. Install wide-angle viewers at eye level on all exterior doors. If you have to open your door to see, your locks won't do you much good. Try to find peep holes with covers to prevent people from looking back in with special tools, like a reverse peephole viewer.
For maximum security, your exterior doors should be windowless, and you should not have windows close enough to the door so that a thief could break the window and unlock the door from the inside. If you do have sliding glass doors, glass door panels or nearby windows, however, cover the glass with a security grate or grille on the outside or a clear, unbreakable polycarbonate panel secured behind the glass on the inside.
Secure sliding doors. The best way to secure sliding doors is to install keyed locks at the top and bottom. You can also make or purchase a bar that swings down from the door frame to the middle of the door to prevent the door from sliding. At the very least, place a rod (a thick wooden dowel, for example) in the bottom track of the door to keep it from being opened. Regardless of the method you use, it's a good idea to reinforce the glass with polycarbonate panels as recommended in the previous step.