Digital camera that takes images at resolution needed for end usage. Most digital cameras are adequate for the job. Cell phone cameras are not suitable.
Ample natural light or flash to compensate.
Pick a nice day. Sunny and partly cloudy is ideal. Overcast, if not too dark, can also work well as it avoids strong shadows that can darken out areas of interest such as a covered entry.
multiple shots from different angles.
Shoot the same subject from different angles. You may find another angle to be better than what appeared to be the best at the time of the shoot.
Steady hand, fast shutter and/or tripod
A tripod is the best way to ensure a properly focused shot. They are light weight, portable and inexpensive. Check the bottom of your camera for the mount receptor (a hole that will accept the tripod mounting screw) and purchase the appropriate size to accomodate you camera.
NEXT: Taking Exterior Shots