"Not that her parents would have entirely agreed with the supposition that there might have been that in his character which, had he not felt himself unequal to the task which affected him not a little in its apparent issue, even though actually simple in its ultimate object, it would have been possible for him to utilise to such an extent that he might not have entirely disappointed their none too sanguine estimate of his ability."
I admit that all amateurs do not rise to such cloud-wrapped heights; but many are nearly as bad!
Then, again, I have known the idea the author had in view when he started a paragraph, to get lost half-way through! This is due to the fact that the mind has not been trained to sustain consecutive thinking, but is permitted to veer round to all points of the compass like a weather-cock.
"Every Why hath a Wherefore"
If you enunciate a problem, see that you give the solution. If you start to elucidate some theory (or the reader is led to believe that you are going to elucidate it), do not forget all about it, and switch off to something else.
If you have no solution to offer, it is wiser and more satisfactory, as a general rule, not to put forward a problem at the close. A sense of incompleteness—or of something still awaiting fulfilment—is as disastrous to the success of an article as it is to the success of a book.
Undesirables
Beware of labouring a thought. If your point is only a slight one, do not reiterate it in various forms or over-embellish it.
If no big idea lies behind your sentences, no amount of impressive, ornate language will make your writing great.
People sometimes think that a fanciful style of writing will hide defects; whereas, on the contrary, it often emphasises them.