Let us begin in our quest to eliminate redundancy with the word redundancy itself, along with tautology and pleonasm. These are roughly synonymous, but if correctly used they do have shades of difference.
To begin with, do not say "pleonasm" in polite company. When you do say it, use it to refer to syntactic rather than semantic redundancies. For example, call the phrase "I know that you are coming" a pleonasm (because of the unnecessary "that") but the phrase "Could you repeat that again?" where "again" is totally unnecessary, should be termed a "redundancy." Although you would not be wrong to call the latter a pleonasm, use "redundancy" so as not to be redundant. Use "tautology" only amongst logicians to show that you can recognize dual propositions that have some pretense at differentiation but are actually saying the same thing. To wit: "It's very important for folks to understand that when there's more trade, there's more commerce" (George W. Bush, at the Summit of the Americas in Quebec City, April 21, 2001).
The greatest redundancy is, of course, the universe itself, which seems to be replicated over and over in every individual's consciousness, for no apparent reason. Perhaps it is due to some inherent principle of extravagance in nature. Did it never enter the mind of God that it would save a considerable amount of effort to simply create one universe rather than many? The recent presidential election showed, however, that despite appearances people definitely inhabit different universes, some of them very different indeed.
It is a wonder any of us can communicate at all. Luckily, redundancies are rife in common parlance and fill up the space that would otherwise be used for understanding each other.