My own pet peeve is the use of "hard" in place of "difficult". Whilst not been strictly incorrect "difficult" refers to a problem or challenge whilst "hard" refers more to an object. Yes I know there is a common usage for "hard" being used for a problem but its a pet peeve of mine and just grates on me every time I hear it (which is often). Over-use intensifiers are similar in that they are not incorrect, but just lazy speech.
One of my favourite reads, when I was young, was Usage and Abusage by Eric Partridge (have two copies of it), which probably says it all
But see the more interesting one's at https://lifehacker.com/are-you-making-these-common-grammatical-mistakes-1836969914
#grammar Are You Making These Common Grammatical Mistakes?
No one can recognize our relentless misuse of the English language quite like an editor. Misplace a modifier, and your editor will (hopefully) let you know. Over-use intensifiers such as â€œvery,â€ â€œjust,â€ and â€œreally,â€ and your editor will tell you that youâ€™re really just not doing your writing any favors. My editor here at Lifehacker has officially broken me of the overuse of â€œoftentimes,â€ which, as she pointed out, isnâ€™t exactly wrong, but is just a longer way of saying â€œoften.â€