Filters, filters and filters
Except for 2 situations, using filters is a bad excuse for not knowing how to post process. First, the only way to block reflecting light is with a polarizing filter. Second, the only way to evenly limit light from entering the camera is with a neutral density filter.
For any other effect, post-processing skills will get you what you want.
The only filters I have carried for the past 10 years are the polarizing filter and an assortment of ND filters. I don’t even carry graduated ND filters, as I find it way too easy and more accurate to simply manually blend multiple bracketed exposures in Photoshop. I stopped using the variable ND filters many years ago as they terribly, did I say terribly reduce sharpness, but also if pushed too far, generate all types of bizarre uneven light and dark splotches in your image! If you must use these, don’t “cross your steams too far” or technically speaking, go past about 4-5 stops of blockage.
I also create a "filter cocktail" to achieve a very fun look. I stack three filters, 8stop and 4 stop ND with a Polarizing filter. The polarizing filter equals 2 stops of blocked light, and this gives me the following daylight exposure: f/22, ISO 100, 30 second exposure
What happens in front of the lens during the daylight hours for those 30 seconds is up to you. If it is cloudy you may need a full minute or alter your aperture to F16. I am in the process of upgrading my Hoya glass filters to the new Lee “Big Stopper” which is 10 stops. I will stack this with either a single polarizer or additional 2 stop ND.
Life is short, take pictures!