Never add a filter unless the benefit outweighs the disadvantage. The major disadvantage is, a filter add two polished surfaces that prompt a light loss due to reflection. A coated filter reduces the light loss from reflections to about 2%. The most commonly mounted filter is a UV. This filter absorbs ultraviolet light and this is helpful because distant landscapes and aerial shots are likely views through atmospheric haze. The UV filter penetrates, to some degree this haze. The UV filter is likely redundant on a digital camera because the image sensor protective cover is also a UV filter. Most folks mount a UV to protect their cherished optics from scratches.

My advice is to buy a polarizing filter. Hands down, this is the most valuable filter for the digital photographer. The polarizing screen filter darkens blue sky causing clouds to standout boldly. A polarizing filter also cuts haze like a UV. A polarizing filter mitigates reflections from non-conductors like glass, plastics, and painted surfaces. Also a polarizing filter allows some penetration so objects near the water’s surface can be imaged. These come in two flavors, buy a circular polarizer.