Using filters in your landscape photography or any area of your photography is a big decision for any photographer and as such you need to ensure you by the right filters for you and also manage the start.
The decision to start using filters is a question all photographers face at some point especially landscape photographers and this article will help you through this process?
But why use filters is the first question you need to answer? Often our images are impacted by the dynamic range within the shot being too wide for the camera to mange. In simple terms the difference between the brightest and darkest are is too big. Using filters we can darken down that bright zone and so narrow the difference between the lightest and darkest zone to a point where the difference is within the cameras range. The other result of this is you will have greater editing range as well. Another reason to use filters is when we cant achieve a slow enough shutter speed i.e. when we want the water in an image to blur. Because filter can be used to darken an image we are able to achieve slower shutter speeds.
If these two reasons are not things that you want to achieve then I would not recommend you acquire a filter system for your photography!
If they are then this may help -