"That must must have taken lots of skill to make. I can't see a single brush stroke!"Modern painters are very disappointing in that, since many of them leave brush strokes everywhere: The first thing they learn at art school is that smooth gradations require merely a good brush and lots of patience - or a camera. It is the equivalent of teaching oneself to write in a perfect printer's font to hide all signs of personality in one's handwriting. Um, why become an artist if you want to keep your personality hidden? Try bookkeeping. Just saying the magic words "I am an accountant" will make people stop prying instantly. (My sympathies to all poor souls trapped in the actuarial trade. I'm sure that making a stable income that is five times higher than the average, haphazard earnings of an artist feels like just compensation for the fact that we get all the best girls. And I don't know why this doesn't work for female artists. Men are idiots, sorry.)
Aspects that make a good picture:
Rhythm, balance, flow of lines, colour harmony, liveliness, unity, personality, thought provoking...
Begin by drawing an imaginary line through the centre of the picture. Then look for all parts of similar colour on each side and see how they balance. Mind, even a tiny dot of yellow on the left can weigh up to a sea of it on the right - if it is well placed. You will hear a lot of that sort of thing. If judging a picture was easy, we would have children do it. They have not learned to lie to themselves yet.
Um, you know, there are books on this subject. Go read a few.