This article is focused on the activity of taking pictures known as photography rather than discussing the tools to take a picture.
1) If you want to improve your photography, study your subject well, write down the skills or things you need to master and PRACTICE PRACTICE PRACTICE and then PRACTICE some more one skill at a time until you have it mastered, then move on to the next skill you feel you need to master.
2) If you want to become a photographer and not a snap shooter, don't spend hours in front of your computer reading camera specs or photography forums. The information contained in them can be interesting and sometimes helpful, BUT if you spend more hours reading rather than shooting, you won't get far as polishing your skills and practicing goes. Read them only when you need to know information contained in them.
3) Owning a camera doesn't make you a photographer, your results are what matters. Anyone can buy a camera these days and call itself a photographer, but there are photographers and PHOTOGRAPHERS.
4) If you think that owning X or F camera brand will make you a great photographer or that if you owned top of the line lenses, your pictures would look better; you are SO WRONG. A great photography is a great photography regardless if it was taken with a cellphone camera or a $1,000,000 camera. Cameras and lenses are just tools, it's what you do with them that counts.
5) Owning the most expensive equipment or the brand that most of your pals use won't make you a better photographer. Only PRACTICE and EXPERIENCE will.
6) There's no such thing as a perfect lens or camera, every lens and camera will have some flaw in it. Stop going over pages and pages of lens reviews that point out the flaws of it at a view of 1000x. Only pixel peepers look at photographs one pixel at a time, the rest of people look at the big picture a.k.a the photograph you took.
7) Regardless of what you think, even the most expensive lenses have flaws in them. Optical and light physics enter into the equation and therefore there will be always something in a lens that's not optimal. Usually lens or sensor tests bring out the flaws in them on tests that look at the results at a microscopic view. Lenses these days are pretty much good enough in all the price ranges to make good photographs. A $250 lens can make great pictures as well as a $1800 lens can. IT'S WHAT YOU DO WITH IT THAT COUNTS, NOT HOW MUCH SPECIAL GLASS OR COATINGS YOUR LENS HAS.
Regular people will not tell you: "This picture could have been so much better if you only used a Carl Zeiss 24-70mm f/2.8 lens"
If you're a pixel peeper, this point won't apply since you will be looking for the slightest thing wrong in every pixel of an image, therefore you WILL need to get lenses that have no color aberration or flare or any flaw at 10mm or less or at 1200mm or more; or cameras with a sensor that doesn't show any noise from ISO 50 to ISO 3,000,000. GOOD LUCK WITH THAT.
8) No matter what you think or have been told about noise; IT'S ALWAYS BETTER TO HAVE A NOISY PICTURE THAN NO PICTURE AT ALL.
9) When buying a camera, select the one you feel the most comfortable with, it will be a tool of regular use, and if you're not comfortable with it, you just won't get along with it. Do not buy a specific brand just to please your friends/mentor/boss/wife/husband/teacher/etc. or be part of the group that uses R camera brand.
10) Buy books or look for information on the Internet about photography, read them and take down notes, write down the points you feel you could improve on and do point 1.
11) When working to master skills, work on one at a time and then move on to the next one. If you do 3 or more at a time, you won't put your full attention on them and may overwhelm yourself and just drop it.
12) Always have the last word on how your picture looks, be open to suggestions if they will help you improve, but always stick to your vision and NEVER waiver on it just to please a bitter photographer who is supposed to be a savant on the subject but just criticizes your photo to make you feel wrong about it.
13) In photography there are 3 main axioms to keep in mind at ALL times:
a) In photography; LIGHT is EVERYTHING
b) In photography; COMPOSITION is what will make a GOOD photograph.
c) Knowing the subject of photography will guarantee you CONTROL over how your pictures come out.
14) If you think you don't need to know what aperture, f/stop, shutter speed, ISO, etc. mean, you're not a photographer, you're a dilettante.
Dilettante: Someone who takes something serious as a game or a hobby.
15) Share your knowledge and expertise with other people. Knowledge is for everyone, not just for a small circle.
16) There's no such thing as positive criticism. There are critics, which are meant to degrade or to discourage you and there are suggestions, which are options you can look into to improve your skills or have in mind for next time or to experiment, but its completely up to you what you do with them, unlike criticism; that one you're supposed to take it and suck it up.
17) There will be people who will genuinely try to help you without interfering with your work and there will be people who will openly or covertly try to stop you, discourage you or make you end up taking pictures like them. From the first group learn everything you can, from the second group learn what NOT to do to other photographers.
18) Having a long time practicing photography doesn't mean one is great. Results are the way to measure how good or bad someone is. Having 40 years of doing the same thing is only useful to show off at parties, but practically it doesn't mean squat if your pictures aren't great.
19) Don't get stuck on the same subject or style or kind of photography, etc. Always be open to try new things, experiment and always try to do something new.
20) Develop your OWN style, not a style that it's been overdone to death by a thousand people before you. Being original is a lot more fun than being the copy of the copy of the copy of the copy of the copy of the copy...
By this I don't mean that you don't try a subject already done, what I mean is that you don't shoot like someone else has or does, show the world how YOU see the subject you're working on.
21) Don't do something to another photographer that you wouldn't like that someone else did to you.