The majority of photos needs a touch up (unless you know what you are doing or are Amazon of course with the patent for photographing an object against a white background. It needs no touching up.)
I took the photo below which was more for the record of the area rather than get a great photo. I probably would have gone at a different time of day to try and achieve better light if I had time. It’s underexposed (deliberately) and the sky was a wash out.
I decided I would replace the sky…. I’ve never been keen on this because I think it detracts from the effort that a photographer puts in to get the perfect shot. If you’ve only got one chance to get a photo though, should it be okay to put in a new sky? Probably yes as long as you don’t enter the photo into a competition. I used a combination of Photoshop and Lightroom to alter the photo.
cranbury attic photography 
Go as far as you like; it’s your photo and your vision.
Personally, I don’t replace elements or add new elements to an existing image. Instead — with digital and slide film — I expose for the highlights; with negative film I expose for the shadows. Then I go from there.
There was a time when I felt that images shouldn’t be altered in *any* way (and indeed they can’t if you’re shooting slides for projection purposes). However, I ditched that mindset long ago and now consider post-processing to be the second half — or more — of my image creation process.
You’ll find that some images work almost perfectly straight out of the camera, and others require heavy post-processing to achieve your vision of how it should look. Still others have to wait — maybe for years — until technology can catch up to what you had in mind.
All that said, play with your image. If it has good composition, see what happens when you apply different actions to the image; do they elevate or detract from it? Don’t feel that one sitting is necessarily the end of your quest; I have images that I shot well over a decade ago that work as a composition, but haven’t yet reached the point where I’m satisfied with them.
Hi Mitch
Thanks for the great comment and for for liking my photos. Much appreciated.
Yes, I think at the end of the day, you’re trying to get the best picture you can from what you’ve got. I guess the less you need to do, the more satisfied you are with the picture as you’ve got it right in the camera. Generally I would removed minor things if I thought they detracted from the picture, but anything more than that then it becomes a bit of an effort anyway! I think sky is one of those things, that if it’s the only thing that’s not worked in the picture then it’s worth doing something about – again if I was a for a competition adding and removing things isn’t really an option.
I also agree with you about older images. As I’ve learned more about what I can do with my pictures, looking back at older ones gives them a new lease of life, and I guess as I learn even more, then I can look back again in a few years time and do something else with them. Endless possibilities.
Thanks again.