You ever read a sentence and, once you get to the end, you can't remember where you started? They can make you crazy as a reader, but for writers, they're remarkably easy to create. Often, they're a symptom of trying to fit too much information into a sentence.
One form of the convoluted sentence is the sentence with too many dependent clauses. We state a point, but before we go on to our next point, we feel it necessary to clarify the who/what/why of our thought. But then, the same questions come up for the clarification itself, and so on and so forth until we've drilled ourselves into the rhetorical ground.
A dependent clause is a clump of words whose existence in the sentence depends on another clump of words. For example,
I went to the store to buy a bottle of milk.
"I went to the store" is what's called an independent clause. It can sit all by itself, and it's still perfectly grammatical and understandable. But "to buy a bottle of milk" only exists to answer a question about the independent clause. That, is, why did you go to the store? Its presence in the sentence is dependent on the existence of the first bit.
Suppose you go on to explain why you bought the bottle of milk:
I went to the store to buy a bottle of milk to feed the cat.
Now you have a clause that's dependent of the dependent clause. "To feed the cat" wouldn't exist without "to buy a bottle of milk," which in turn wouldn't exist without "I went to the store."
I like to think of each dependent clause as a flight of stairs heading down:
I went to the store. (Ground floor.)
(why?) To buy a bottle of milk. (Oh, look, now we're in the basement.)
(why?) To feed the cat. (Ooh, a sub-basement.)
Now this sentence is still understandable. And it's still more or less understandable (if a bit rambly) if you add some more levels to the house:
I went to the store to buy a bottle of milk to feed the cat that lives in the abandoned house that sits on Elm Street.
But what happens if your next sentence is the following?
I ran into my neighbor there.
Which "there" are we talking about? The store, or Elm Street?
Ostensibly, "I ran into my neighbor there" happens on its own ground floor. But now we've drilled so far down explaining ourselves, we've ended up in the sub-sub-sub-basement.
So do we expect the reader to run up four flights of stairs just to get to the next sentence?
This construction gets even more confusing when you're talking about buzzwords/abstractions instead of real, concrete actions and things: "The company is pioneering the innovation that is aimed at helping the customer whose interest is in business-to-business communications that are optimized for maximum effectiveness to grow their business." By the end of the sentence, do we even remember what the company is doing? If the next sentence talks more about the innovation, the reader has to jog up three flights of rhetorical stairs to get back to the topic. And if there's one rule that I think is essential to clear communications, it's this: Don't make your reader do extra work.
How to avoid this? A couple of ways. One, don't feel the need to explain every niggling detail. If you find yourself overexplaining because you are nervous the reader will misinterpret, take a step back and a breath. Remember your readers are already in your field of study; they already know what topic you're talking about. If there's confusion that needs to be remedied, your editor will point it out to you. She's in a far better position to determine what your audience needs to know than you are.
And don't be afraid to use multiple, shorter sentences! Even in formal writing, you can be plain-spoken and clear. If a side point is really important, it's probably worth its own sentence. (Break it into a parenthetical if need be, but don't overuse them.) Sometimes simple sentences, even with boring verbs if necessary, can be the best way to express and explain your point.
Ugh, why'd I add that clause? Or that doubled verb? Let me state it again:
Sometimes simple sentences can be the best way to express your point.
See? Just as understandable as the original. And far less work for you, the reader. But that's another blog post for another day.