Choosing a new deadbolt is similar to buying a new suit. Both low- and high-quality ones look good at first glance. The quality is hidden in the details of how it is assembled and the materials used. Dry-clean an inexpensive suit a couple of times and it no longer hangs or fits properly.
Since you cannot evaluate the inner workings, base your buying decision on price. It is your best indicator of quality. You may not need the most expensive deadbolt with all the bells and whistles, but certainly do not buy the cheapest model at the home center store.
Your first decision is whether to get a single- or double-cylinder lock. A single-cylinder deadbolt has a knob indoors that you turn to lock and unlock the deadbolt. A double-cylinder design requires a key indoors, too.
If your door has glass or sidelights, a single-cylinder deadbolt is not really secure. A determined thief can break the glass, reach in, turn the knob, and be inside your home in 10 seconds.
Check your local codes. A double-cylinder lock may not be allowed. Although it is more secure, you and your family cannot exit your home as quickly in case of a fire or emergency. If you leave the key in the indoor deadbolt, then it is no more secure than a single-cylinder design with a knob.
If your budget is not terribly tight, you might consider one of the new electronic deadbolts with a remote control. You will not have to fumble with keys in the dark. Just push a button and the deadbolt unlocks. There is also an audible and visual signal to let you know if it is locked.
These have a rolling security code so that a thief cannot electronically snatch your code. There are more than one billion codes built into the unit. Every time you open the deadbolt, the code automatically changes.
Installing a deadbolt is not difficult, but your measurements and positioning of the holes must be precise. You must drill three holes: a large one in the face of the door, a small one in the edge of the door, and one in the doorjamb.
To simplify the alignment of the holes, you might consider renting a small lockset jig at your local tool rental shop. A standard height of 36 inches is convenient to operate. If you locate it higher, there is less chance that a thief can give it the full direct force of a kick.
Once you have the deadbolt installed in the door, close it and turn the deadbolt so the latch hits the jamb. Mark the top and bottom locations. To get the proper hole width for a tight, no-jiggle fit, make the hole narrow and slowly open it up with a sharp wood chisel.