I started doing digital photography in 2006 and never looked back. Being an artist who does photography, not the other way around, manipulating images has been a natural progression.
I've been on the photo site, Flickr, for about five years now. In the beginning, I knew absolutely nothing, and now I'm barely intermediate! I still work with point and shoots for several reasons, the biggest being finances, and have had to learn to do post processing in order to create work that was interesting enough to sell, and to show, both of which I've done. I've had one of my shots on the cover of a magazine in South America, and others have been used around the web, and in books.
I would tell you that with this art form, it's the end result that matters, not how you arrived at it. If your camera cost $200 and you pick up a lot of graininess, post processing can help remove some of that. If you have a good shot that could use a better looking sky, you can airbrush in some color, or take out things you don't like. Photoshop is the tool of choice for most, but I couldn't afford it, so I improvised by using free or inexpensive editing tools like Picasa, Picnik, and even the Kodak Easy share editing software that came with my first camera. Photo Explosion is inexpensive, and is fun software to create artsy edits, too. For Facial Retouching, I use Portrait Professional. THAT is a skill that takes some time to do well, and better editing tools make the edits a whole lot more natural! My first attempts were like masks, having hand airbrushed (on the computer) the skin, not using the portrait software. Even my airbrush skills have improved, and I regularly use it to add color or take things I don't want out.
Don't use other peoples' photos. Don't say it's SOOC if it isn't. Don't post your own retouched face and let people think you're perfect if you're not. (Been there, done that! Was convicted, and now post the before's, too!) The ethics come in what you DO with your photos after the fact, and what the content of those photos is. Post processing is fun, artistic, and creates beauty where it was lacking. Our desire to re-create comes from the part of us that is like God, who creates. Nothing wrong with that. Have a blast!
You can see my photos, retouched and unretouched, (I usually show the before and after) on Flickr. Just add /celticsong22 after the web address. There is a group on Flickr, I think it's called "Beginner's Digital Photography", and in the discussion threads there are countless links to free editing software. There are tips on there, too. Until April 19, Picnik, which is Google's editing software, will be available on Flickr. You can play with it and see how you like it. The premium version is free to all for the next month.