What are some resources to learn different photo editing styles?
My default edits are plain-vanilla neutral. Necessary for certain subjects, but boring for others. What would I do different with my photos? I don’t know. I have brain freeze.
“Dark and moody” style is popular, but it doesn’t fit a lot of things I shoot.
Maybe a good photo editing drill is to take a photo and edit it in 3 styles that is not your first impression. But what are they and what are their characteristics?
I don’t start with a style. I start with a statement or a mood or an expression or an emotion. What is this image really about? How can I edit the image to better express that? Or to express how I felt when I took the photo? Or how I now feel, looking at the image?
I might then choose to emphasise or de-emphasise elements. I might raise or lower mid-tones (“light and joyful” or “dark and moody”), raise or lower saturation (“pretty” or “thoughtful”), raise or lower local contrast (altering relative importance or salience), and so on.
I would say I did discover creative editing in 3 ways :
)I sort of went “The good, the bad and the ugly” but in reverse
I did not watch so much tutorials video before finding @s7habo 's that show really clever tricks in the software I used and, watch some but not much photographer “inspirational” video on youtube…
As an example of the Ugly way (fiddling aimlessly and refining after" that landed me satisfactory result :
http://82.64.103.11/clind/photo/public/uploads/medium/5383a485c77c0c822b1198e1a47b0a57.jpg
Indeed this is a fun part of doing some research I think.
Spend some time dissecting photos that provide you a sense of a “style” you might be interested in - browse many photos and begin asking yourself what aspects of it you find interesting.
For instance, I liked the look of some photos that had a very distinct dark green cast to leaves and plants. I have a rough idea of what foliage might look like un-processed and I tried to focus on the specifics of the greens and nearby colors. Then I tried to focus on what needed to be done to sort of emulate this effect and what tools might be available to achieve it. Try some things, repeat.
(I think in my case it was mostly pushing nearby colors into a narrower spectrum and playing with hue/contrast to taste).
This is a path that rewards many examples and thinking out individual steps to draw your image to something similar. Pulling colors one way and possibly balancing in the other direction as needed - a back and forth of experimenting until you begin to get a feeling for what the tools do and how to bend them to your will better. 
Personally, I’m a self-confessional ‘style’ addict — at one point, I was even using git to track my profile changes! Just last night, I spent seven hours solid ‘tweaking’ my PP3s in RT. 
One thing I will say, though, is this: when it comes to your own photos, you’ll always be over-critical — it’s just in our nature. Whenever I get in a rut, I always think of this quote by John Bonham — regarded by many as the greatest and most influential drummer that ever lived:
“I’ve had it with playing drums — everyone plays better than me.”
For me I find defining my processing style starts in the camera before I push the button. I consider what it is that inspires me to take the image and what it is that I am hoping to get out of the image. I consider the story I want to tell, the memory I want to preserve. Then understanding the tools I have for editing the image I capture the shot.
With many of my shots I like to relight the scene by using multiple instances of exposure. I want to draw the viewer to the subject by keeping it lighter and darkening the rest. This is a technique inspired by the landscape works of Ansel Adams.
But of course one style doesn’t fit all images. For me I hate prepackaged picture styles that are available for certian programs. I want to hand craft images as individual works of art. Not the mass produced sausage machine images that some commercial programs produce. That is why I love the artistic creativity of Darktable.
PlawRaw is a great category for seeing how different people see images differently and create very different styles. I have learnt a lot from that category. Some of it being technical skills and some of it being differing artistic perspective.