Whole volumes have been written on photographic composition, which will explain things far better than I can. Not being artistically trained, I’ve tried to read a few, but I’m not sure how much has sunk in – I think I’ve learned more by looking at the work of others and seeing what works.
I tend to compose intuitively, but not randomly. Although I understand things like the rules of thirds, I don’t set out to either follow or break these supposed rules. I just shoot what looks right.
The only principles I tend to follow are to either have a point of interest (focal point) or if not, I try to at least make it a picture of something. Oh, and fill the frame!
Having sat and stared at my pictures for long enough, here’s some themes I’ve picked out.
Symmetry

Foreground interest

Close up

Side On

Strong Colour

Wonky Angle (no-one said the picture had to be either portrait or lanscape format!)

Dominant Subject

Looking Up

Looking Down

Looking Through a Window

Hope this is of use to someone!