In the days of film, when we did not have special effects of digital post processing, we had star filters and dozens of other special effects filters.
Now, about the only image modifying filters used are gradient filters to keep from overexposing the sky, or ND filters to allow you to use a wide aperture in bright light. Polarizing filters will reduce reflections coming from water, and in any situation where the light is polarized.
UV filters, at least good ones should not affect your image.
Perhaps you can post one of your problem images along with the camera settings, and tell us what it is that you want to improve. The term better looking is very vague.