Because its an outdoor cameras it is mandatory that it is vandal proof camera, Since its outdoor and is potentially unprotected from crooks who vandalize the camera, you need to make sure its vandal proof.

Of course cameras are not always installed under a portico or shade and hence need to be a weather proof security camera to withstand in rain and hot sun.

Must have built in infra red LED's for night vision, i.e if the visibility is almost zero or else you can get away with a day/night cameras, also called as a color/black and white security camera. A day/night or a infra red security camera essentially spits out color pictures in day light and switches itself into black and white mode once it goes below its specified light threshold.

If you are using a full bodied camera with a lens then consider the following.

Make sure you buy a camera with Day/Night feature and also a similar lens that is specified for Day/Night security cameras.

If your premises is very security critical and has no lighting at all, use of infra red illuminator is suggested.

Use a Vandal proof housing and bracket. Mount the camera as high as possible.

If there is a heater and blower in the housing, it is even better. This will make sure that there is no fog on the housing mirror. Some special jobs where housing are used are attached with wipers to combat in rainy days.

Hope this information is useful and helps you to make your premises secure.