Murder your darlings

General Principles

Avoid definitions. Mostly, people can figure out what you mean without doubt from the context. Only use definitions when you are using a word in a specific way that does not align with its ordinary meaning.

Specific examples

For the avoidance of doubt: This is an explicit acknowledgment that what you have just written contains doubt. You are a solicitor: a wordwright; an officer of the Queen’s English. You have a qualification in the unambigous conveyance of ideas. Physician, heal thyself.
[insert general expression] (including, without limitation ...): logically does not, and cannot, add or subtract from the general expression. It is either the statement of the logically inevitable (if the stated instance indeed is an example of the general expression) or it is flat out wrong (if it is not) - in which case change the general expression.
- Example: don't define “Tax” if all you mean by it is any tax, duty, excise, deduction, witholding, impost. [... improvise freely] ... or levy imposed by a competent authority having power to tax.... If your construction will, you know, show up on the Google as a synonym for “tax”, then write “tax”.
Use the active tense. Avoid the passive whenever you can.

... unless otherwise agreed by the parties: This is true of every English law contract there ever was. The clue is the definition of “contract”. It’s an agreement between the parties.
and/or: logically, that means “or".
express or implied ...: that's it: you've covered the universe of possible statements there.
whether orally or in writing...: so does that include, like, body language? arched eyebrows?
We reserve the right to ... - Wait a minute: Did you just give that right away? If so, you can't reserve it. If you didn't, you've still got it, so — you know — shut up already.
", whether ... or otherwise," - kill it. Go on, just kill it. You'll feel so much better.
We may, but shall not be obligated to, ...: collapses quite happily down to “we may ...”.
And while we're on the subject of obligations, “obligated” is only a word if you have some kind of aversion to verbs: It is a verb, inevitably used in the passive (I am obliged) that was then nominalised into a noun (I am subject to an obligation) and then inexpertly converted back to a verb again (I am obligated). There's a better, active, English verb: “must”.
Please be advised/please be aware/please note: If your intended audience is reading and has the intellectual capacity to comprehend your prose, you may be assured it is being advised, becoming aware, and taking note. If it is not, asking an audient to do so won't make a damn of difference.
The parties agree that...: A curiously redundant thing to write, it being an agreement and everything. Try something novel - don't say it.