A few small tips that can make a big difference.
Language evolves. Be open to the idea that a rule you have stuck to for years may have changed.
The serial comma (or Harvard comma or Oxford comma) tends to be used in North America, but is usually only used in the UK if the meaning of the sentence would be ambiguous without it.
Non-fiction writing tends not to use contractions, so don’t, can’t and won’t need to be do not, cannot and will not.
This is a debated topic but most publishers now use a capital B when describing Black people/culture. (The ‘w’ of white is lowercase.)
The word ‘internet’ is now recognised as taking a lowercase ‘i’.
Some things, however, never change:
Keeping sentences to less than 50 words improves the readability of your work.
‘Under way’ is two words. In any country.
Superscript footnote numbers always come after punctuation, not before.