Well, personally I like Tiffin filters, they seem to exceptionally get the job done.
But if you want a full list of nessecary filters, here you go:
-Skylight/UV filter is A MUST. It protects you lens as well as eliminates UV haze.
-Circular polarizer (not to be confused with a linear polarizer). These are filters that eliminate reflections, like off of windows and water and such, and increase contrast and deepen the blues. You've probably seen pictures where the sky is soo blue and then fades up to black or almost black. They used a CPL.
-Neutral density. These filters come in a variety of degress, such as 0.8 or 0.9x. They darken the image, allowing you to shoot in lower shutter speeds with low f-stops.
Hope this helps.
