Some pretty good advice here, especially what Volguus said: take a lot of pictures in a lot of different conditions. I have no formal training but I've taken about 200,000 shots in the last 3 1/2 years. If you do that and spend time developing your craft, you'll improve.
Another recommendation would be to take a few of your best shots - ones you think are absolutely perfect - and post them for serious critique. Unfortunately, they won't be perfect, and you can learn a lot of the finer points that way. Putting shots up on this forum usually results in comments of "great pics!" from almost everyone. Sometimes it's frankly not true, but a lot of us aren't about to jump in and give someone a serious critique when they haven't asked for it.
So, when posting your pics, ask for that serious critique, swallow your pride, and take the suggestions. When considering the suggestions, know your source. Everyone will have advice, but take the advice from people whose photos you admire.
City Photos on this forum is not the place to get critique, since most readers there are urban enthusiasts and maybe picture takers, but not serious photographers. In that situation, people tend to judge the beauty of the subject matter rather than the quality of the photo. (IE,
a mediocre photo of the NYC skyline would get more praise than a
better photo of an ordinary streetscape.)
General Photography is better, since many of the more proficient photographers on SSP visit here. But I would recommend going to other forums that are more centered specifically on photography. I found
ThePhotoForum.com to be pretty good. They have a section for critique.
99% of pros use photoshopping to some degree, so don't be discouraged from it by those who say their pics weren't edited at all. Usually when I see that, my thoughts are "they needed to be." Just don't overdo it. People will tell you if you've overdone it as part of the critiques.
Good luck and take a lot of shots!