Choose a baby gate that installs with hardware and not pressure. There are two types of baby gates: pressure-mounted gates and hardware-mounted gates. Pressure-mounted gates stand up by putting pressure on the walls next to them, while hardware-mounted gates actually screw in the wall. "The New Parents’ Guide" says that in most situations, either style is fine, but for a gate at the top of the stairs, parents should only use the hardware-mounted style. While pressure-mounted gates generally work fine, there is a small chance that the baby or toddler could push the gate over, and that is not a chance to take.
Measure the height and width of the area where the gate will be, to determine what size gate to buy. Some gates are easy for toddlers to open, so keep that in mind if you have a toddler.
Choose a wall-mounting kit that will work for your banister if you have one. Hardware-mounted gates require a straight surface for installation, and a wall-mounting kit attaches to the banister and gives the gate a straight surface to attach to. If the wall opposite the banister does not have a wall stud, you will need to purchase a wall-mounting kit for that wall, too. Using a magnetic stud finder is an easy way to find out where your wall studs are.