One thing I've heard of and tried is to shoot outside of your comfort zone. Sometimes even finding the limits of your comfort zone can be telling.
Tell us about your comfort zone, if you know it well. I've got to take off to eat, wife is starving and on the way home.
Comfort Zone? I am not sure if I have any.
I have a bit of an apprehension approaching people on the street for photographs, especially ones that they would mind (beggars, junkies, etc) and sometimes my shyness gets the better of me, but like I've written before it is my focus and personal struggle and fighting with it since I first picked up a camera.
Subject matter, I don't do landscapes, because I find them not interesting to me, but I try once in a while to find something unique.
Cameras? I usually carry my Hasselblad everywhere and in places people would afraid to have such a camera, but I've shot with everything, from the cheapest compact I could get, Holga, 35mm SLR and now I am learning a pinhole. I have also ordered a Rolleiflex to help me with the street photos.
I like the square, but I've shot a lot with the 35mm rectangle and I would love an extreme panoramic camera if I had the money for it and the enlarger.
I don't mind out of focus, blurring, cut off details, lost highlights and shadow detail, weird compositions, etc. Not only I don't mind, but often I specifically go for those, even more lately.
I also like experiments in the darkroom with blurring filters, dodging and burning, lith, polarization, toning, anything really.
I don't do montages, because I can draw, so they are useless to my "vision".
If I have a style of photography I love more than anything else, that would be of Magnum photographers, which as style is varied, but it has that gutsy, photoreportage I love.