I'm about to head out for Ireland, so don't expect me to put down the mug of Guinness long enough to type. :) Also this is a village remote enough that wireless doesn't reach. There is an internet cafe, so I'll check in, but ... holiday! (Well, I'm taking 4 mss to edit, and I'm sort of wondering how well that'll mix with the Guinness.)
Theresa's brilliantly handled this subject, but I'll just weigh in quickly with something Mary Buckham pointed out in a workshop-- that the end of a paragraph is important too, and it's effective to end on a word or phrase of conflict or tension. And it's worth rewriting the last sentence to get that tension.
So if you have:
It was torment for her.
Easy to revise it so that the "conflict word" comes last:
For her, it was torment.
Not every paragraph has to end this way, of course. But think about which paragraphs need more zing, like paragraphs of introspection or description. It might not even be conflict, but meaning or a concrete image that you want to leave with the reader.
And his airplane models dangled above it all.
And, dangling above it all, were his airplane models.
Notice that sometimes you sacrifice conciseness (bring on the reversed construction here!) to get this tension. But often that's good, as the length of the final sentence in a paragraph has meaning too. A longer sentence draws out the experience, while a shorter one cuts it short (longer or shorter than the other sentences nearby, that is). So go with a longer sentence there at the end if you want the meaning to linger, and shorter if you want emphasis.
Mary Buckham took us all through a few of our own paragraphs to experiment with this, and I was interested that frequently we decided the tension-word was a noun-- that is, the most concrete of word types. But verbs can work too:
So he ran.
Ran is a pretty ordinary word, but nonetheless, it's got power and tension. I thought of replacing that with a more evocative verb (dashed, sprinted), but they all seemed to require "away," and that isn't a tension word. Run has the benefit of simplicity. It's one of those "strong verbs" that are about as old as the language itself, and so has picked up multiple meanings (like "freedom"-- the "run of the place") which are embedded in there even if we're using the most basic meaning (walking very fast :). And of course, running is all about motion, escape, fear, excitement. It conveys emotion as well as motion.
Those strong hard Old English verbs can be good paragraph enders. We often want to replace them with the synonyms that have come into the language from other languages, to avoid repetition or convey nuance. But these are often the verbs with tension. They mean business.
So, anyway, must go pack (carry-on only! For two weeks!!!). But if you think your paragraphs are too long, or they end on a whimper instead of a bang, you might go through your sentences and find one that conveys that sense of tension, of conflict, of power-- and find the right word to end on. Then break there.