DSLRTips has a short introduction where you could learn how to use polarizing filters. You can also read about it in Luminious-landscape , France in photos and most importantly, Ching-Kuang Shen has an excellent explanation of how this works with polarizing filters.
What are you using to clean your lenses? After reading about the use of Vodka from Justin Low, I took and searched around for alternatives. Remember that you always follow the advice on the 
Internet at their own risk and it is probably a good idea to check this stuff both one and two times before testing yourself. Someone on a forum mentioned that he used another alcoholic and that the liner had disappeared along with fingerprints. It also provides that vodka should be diluted with water distilled.
Digital photography school has made a simple compilation of different options and what you can think of. Some simple advice is to use UV or Skylightfilter to protect the lens. I got the advice from one professional photographer not using filters at all. Depends how clumsy you are. Remember to start simple before taking out the heavy artillery. It may well be enough to breathe on the lens and use microcloth (do not use paper).
Remember to blow away particles before using cleaning fluid. Someone is using tape to remove fingerprints and other debris from their filter (maybe not to recommend the expensive lenses, however). It seems HOUSEHOLD REMEDY limits are as many as photographers.
How do you clean your lenses?
Use Gimp and G’mic to warholize your own photo. I took my photo and used the filters in G’mic to make it like this. Using G’Mic is both fun and can be useful. I use it both to get rid of noise and sharpen my images, but of course you can have fun with alot of different filters.
I strongly recommend that you use filters like this and play around with layers. You better learn the fundamentals of your editing program since it will learn how to make your photos pop. The old masters like Ansel Adams stayed very long in the darkroom. Your darkroom will be your editing program.
Greyc’s Storation has always been a competent noisereduction filter for Gimp. GMic or Greyc’s Magic Image Converter is developed of the same people. They have improved the GUI and came up with more scripts and filters and collected them in a new toolbox for your enjoyment.
You can easily create polaroids, do mosaic or simulate a fisheye lens. The really good stuff is the noisereduction that will save your day if you want a pic clean of noise. If you want something that make your pictures extraordinary i advice you to really get into advanced imageediting but scriptcollections like GMic will help you and be a support. Just don’t rely on filters will do the work for you.
Here is some examples what GMic is able to create for you. On their site you also will find a collection of examples what their filters can do.
Don’t miss the resource page about Gimp. You will find many useful links to great Gimpsites there.
FishEye
Drawing
Noisereduction
