I have a Tameron 18-270mm I am just starting to use ND. Can a none suggest the proper one to use with this type lens? I prefer screw on. The camera is Nikon D60. Thanks everyone and happy shooting!
Elaine O has the right idea. Individual screw on filters have to be for a specific lens. If you have several different size filters then you need several different filters. Some filters can cost you $400 or more so that could get really expensive, not to mention that you will have to be able to keep track of which filter goes on which lens.
As for giving you advice on how to use them one would first have to ask what are you using them for? What kind of photo are you trying to take? There is sort of a SWAG factor in the beginning so the best thing to do is experiment and make detailed notes. When in doubt check out YouTube for tutorials.