1. Wordy Phrases. Many compound phrases do not compound meaning. They are either repetitive or have one-word equivalents. Frequently, "legalistic" language is an offender; phrases that use too many relative pronouns (who, that, which) cause clutter and confuse your reader. Even articles can be excessive (the word "the" wears out quickly when used excessively in a single sentence).

Poor
this is to inform you that we have
for the sum of
in the event that
on the occasion of
prior to the start of
a small number of
during the time that
due to the fact that
in the same way
at an early date
remember the fact that
not in a position
most of the time
in view of the fact that
until such time when
we are of the opinion that
with reference to
without further delay
as a result of
for the month of December

Improved
we have

for
if
on
before
few
while
because
similarly
soon
remember
unable
unusually
since
when
we believe
about/regarding
now/immediately
because
for December

2. Infinitive Substitutes. Whenever a phrase substitutes for an infinitive (the verb form with "to" in front of it, giving it no particular tense, person, or subject), the sentence will be longer, and your meaning will be harder to get. Using the infinitive gets to the point sooner and makes your purpose clearer.

Poor
In order to be a successful writer, hard work is necessary.
He went to the library for the purpose of studying.
The employer increased the salaries so that he could improve morale.

Improved
Hard work is necessary to be a successful writer.
He went to the library to study.
The employer increased salaries to improve morale.

3. Obsolete Phrases. Obsolete phrases are simply out-of-date phrases. They contribute to tiresome sentences. They increase sentence length. They come between you and the reader. Need any more reasons to get rid of them? The best way to figure out whether your phrasing is obsolete is to ask yourself, "Would I say it this way if I were talking to this person face to face?" If the answer is no, get out your red pen and find a better way to say it.

Obsolete
beg to state
as per your communication
hoping to hear from you
soon, we remain
in response to same
yours of the 12th
awaiting your reply, we are
in due course
permit me to say that
we are in receipt of
pursuant to
in closing, I'd like to say
accordance to our records
attach herewith is
kindly advice
this will acknowledge
contents duly noted
as stated above

Up-to-Date
(omit)
as in your e-mail/phone call/letter
(omit)
in response
your e-mail of June 12
(omit)
today; tomorrow (or a specific time and date)
(permission is not necessary; just say what you wish)
we have received
(omit)
(omit)
we find
here is
please let us know
thank you for
followed in every detail
as I have said

By getting rid of long, awkward phrases, you clear the way for better understanding between you and your reader-so be bold and let the red ink fly.