One of the first things you need to think about is what the door is made of. A lightweight, hollow-core wooden door is going to be easy to smash through. Ideally, an exterior door should be made of sturdy construction with a solid wood or steel core. It is also very important that the door is in good condition and not displaying signs of rotting, warping, or cracking.
The door lock is an essential security feature. It should be a quality deadbolt lock. If you like the security of a door chain, that is fine but only use one in addition to a deadbolt lock and never instead of it. It is also a good idea to install a bump-resistant lock. This is because bump keys have become a popular option for intruders these days.
Many front doors have glass paneling in them, but this could be a security risk if the lock is situated close to the glass. Try to position the lock far enough away from the glass so that it would be difficult to reach the lock if the glass were smashed.
Installing a peephole is another good option to enhance security as it allows you to check who is at your door before you open it.
Some front doors have a mail slot in them. These should always be fitted with a cage or box that surrounds the mail slot, otherwise, an intruder could gain access to the doors lock from the inside through the slot.
Why not inspect your exterior doors and see if they are equipped with these security features?