Even while you embark into artful syntactic complexity, it is worth remembering that the core to clarity and thus readability lies in the S-V-O relationship.
If your sentence is clear about who the subject is, what the subject is doing, and who he/she/it is doing it to, the reader should be able to process the sentence without trouble. Sometimes the sentence will have only a subject and verb but no object, in which case we're talking about the relationship between subject and verb.
The following sentence makes a statement about a class's response to reading Tony Morrison's Beloved.
The class enjoyed Beloved.
In this example, the subject, verb, and object line up just the way we expect them to in an English sentence: S-V-O. No problem.
Now, a variant:
Beloved was enjoyed by the class.
Here we have six words instead of four: two additional units of meaning for the reader to process (why?). The true subject, or agent, of the action has been taken out of the subject position, which will cause a momentary--though unconscious--blip for the reader as s/he launches into the reading assuming that the word in the subject position is the subject of an active construction. The action is now passive, which, combined with the extra word freight, leaches energy from the sentence.
Here is a third version:
Beloved, which is a book that has won many plaudits for author Tony Morrison, who has recently capped a distinguished career as a novelist by winning the Nobel prize, was enjoyed by the class.
What's this sentence about, anyway? At any rate, we have to wait a long time to get to the verb, which is where the main idea finally gets named.
Now try this fourth version:
There is general agreement that Beloved, which is a book that has won many plaudits for author Tony Morrison, who has recently capped a distinguished career as a novelist by winning the Nobel prize, was in most cases, if not all, enjoyed by the class.
Empty filler introduction. Subject separated by multiple constructions (and a lot of words) from the verb, which is now itself split. The sentence is a total disaster, but it's far less easy to process than the first version. If you get into the habit of displacing the S-V-O relationship, you may tilt toward sentences like the following:
Within the confines of the present study it is apparent that insufficient data are at present available to completely negate the possibility that removal of the above-mentioned substances from the circulation is not a matter of importance.
A couple of suggestions: First, if your subject is syntactically complex, simplify your predicate; if your verb is syntactically complex, simplify your subject. Second, follow long, syntactically complex sentences with short ones. Give your reader a breathing space.