Advice from the Tea Lady 👒 otherwise known as a very simple little Buddhist Monk with far to much time on her hands 🙌

Parenthetical remarks (however relevant) are unnecessary.
It is wrong to ever split an infinitive.
Contractions aren’t necessary.
Foreign words and phrases are not apropos.
One should never generalise
Eliminate quotations. As Ralph Waldo Emerson once said: ‘I hate quotations. Tell me what youknow.’.
Comparisons are as bad as clichés.
Don’t be redundant; don’t use more words than necessary; it’s highly superfluous.
Profanity sucks.
Be more or less specific.
Understatement is always best.
Exaggeration is a billion times worse than understatement.
One-word sentences? Eliminate.
The passive voice is to be avoided.
Go round the barn at high noon to avoid colloquialisms.
Even if a mixed metaphor sings, it should be derailed.
Who needs rhetorical questions?

Each pronoun agrees with their antecedent.
Verbs has to agree with their subjects
Watch out for irregular verbs which has creeped into our language
Don’t use no double negatives
Join clauses good, like a conjunction should
In letters themes reports articles and stuff like that we use commas to keep a string of items apart
Don’t use commas, which aren’t necessary
Its important to use apostrophe’s right.
Don’t abbrev.
Check to see if you any words out.
In my opinion I think that an author when s/he is writing shouldn’t get into the habit of making use of too many unnecessary words that s/he does not need in order to put his/her message across.
As far as incomplete constructions, they are wrong.
Last but not least, lay off clichés.