Welcome

Think first. Then click.

What story are you trying to tell? Then, consider composition, 'rule of thirds' and the 'golden mean' as guides (lots of references on the internet). 

Good measurement: "If you can print what you were thinking when you made the image, you're a photographer." Also, you're a "professional photographer" if a majority of your income comes from image making. (Argue with a pro about this at your own risk :)

Practice, practice. Even pros are continuously sharpening their skills.

Use "Program" (Auto) Mode at first.

Then experiment with "Shutter Priority" and "Aperture Priority" and "Manual" Mode based on image file info. It seems backwards, remember F-22 is 'smaller' (less light captured, more depth of field) than F-5.6 'wider' (more light captured, less depth of field).