Filling The Frame
Just a small tip but a very important one, and that is to Fill The Frame when composing and taking a photograph.
This is a tip I learned from taking photos on transparency films. As the processed transparency is usually the end result, there is no opportunity for cropping the image to bring out the main subject and discarding unwanted areas around the picture. When projecting trannies this is an important consideration. So if you can either get closer to your subject by moving in or by use of a telephoto lens then the subject will become the photograph and not unwanted background elements.
Of course, if the background is important then there is no need to edit them out.
I think that a portrait for example benefits from Filling the Frame, rather than a small subject surrounded by a distracting background.
Again, if this is the intention, carry on - don't be bogged down with too many rules, it's your picture after all.