Here's an easy rule of thumb when you're writing at work: never write a sentence longer than 21 words.
OK, it's extreme. But it will often get you out of trouble.
(Before you explode, let me remind you that phrases containing capital letters can be treated as a single "word" in this situation. Phrases like "Prime Minister of Great Britain" or "Department of Housing and Development". People read them in one gulp, like a single word.)
The 21-word limit is a natural one. That’s roughly 7 phrases, at which point humans tend to run out of short term memory. Readers can’t remember how your sentence began. Even you can’t remember how your sentence began. What a mess.
The danger point occurs at around 21 words: that's when your sentence risks spinning out of control.
If you are having trouble writing a particular sentence, it’s probably too long. Just chop it into two or more sentences. Or shorten the sentence by removing unnecessary words.