Black clothing is generally acceptable to wear to a funeral. Dark suits for men in colors other than black and dark-colored skirts for women are also fitting for a funeral service.
It is generally appropriate to wear clothing that could be worn to a job interview to a funeral. For instance, a black or dark blue pencil skirt would be appropriate. A tailored jacket can also be included in funeral attire. The most conservative choice is usually the most appropriate for a funeral, whether the service is being held in a house of worship or not. To avoid mental associations of the piece of clothing with the funeral, don't buy a new outfit specifically for the funeral