a. To enable the recipient to read the letters more rapidly and to comprehend and remember the important facts or ideas, we should use relatively short paragraphs of between three and eight lines long. In business letters, paragraphs that are made up of only a single sentence are common and perfectly acceptable.
The general recommendation is to analyse the purpose, content, or function of each paragraph of a letters. Any paragraph that covers more than one thing should be rearranged and split it into two paragraphs.
Information given in the middle of long paragraphs is easily overlooked or forgotten altogether. Therefore, important information should be placed in rather noticeable positions. If some unfavorable or negative things are to be said, a good and acceptable strategy is place them in areas of less emphasis.
b. Other universal recommendations to follow while writing business letters: avoid using dangling, unclear modifiers, avoid split infinitives, avoid using clichés and jargon. On the whole, it is better to avoid using colloquial language or slang not to sound too familiar and impolite.
c. Furthermore, choosing positive language will make our letter well-turned. Business writers and speakers recognize that positive, optimistic people are more open to new ideas and change, than are discouraged, unenthusiastic people.
d. Another important characteristic feature of business correspondence is the usage of passive forms when the doer of the action is insignificant.
Your enquiry is being dealt with.
The order has been confirmed.
e. Some redundant words:
Don't use: as otherwise, at about, be of the opinion, both alike, both together, check into,...
Use: otherwise, about, believe, alike, together, check, ...
g. Some useful abbreviations:
a/c – account
appar. – apparently
c. or ca. – approximately, about
cf. – compare
comm. – commerce
Corp. – Corporation
dt – date
e.g. – for example
et al. – and other people
etc. – and so forth
ibid. – in the same book, chapter
i.e. – in other words
Ltd. – Limited
nb. – nota bene
NOO – not on original
p. a. – a year, each year
P&P – postage and packing
pdd – probable date of delivery