Tutoring people to write isn't easy if the would-be writers have poor literacy skills. These should have been learned in primary school but it's amazing how many people don't have them, even teachers I've tutored. They are the tools of our trade. A lot of spelling errors occur because they learn to spell phonetically, so they write as they hear...as in 'new clear family' -- 'outer body experience' -- 'in tacked'. Some students think it doesn't matter but words spelt incorrectly have different meanings to the ones they intended; good punctuation helps us to make sense of our sentences.
Can you pick out the two mistakes in this one? '...were brought up together but who's feelings were far from plutonic for one another'. One is grammatical, the other spelling. And if you can't spot those, how about:
'Jan was emitted to the ward.'
'She had soused out that one of the nurses...'
One of the most frequent clangers I receive is '...would of...' and if you can't figure that one out, there is no hope for you.
'She had nothing to loose' is another.
Apostrophes appear all over the place, where they shouldn't be and when they are needed, they are nowhere to be found.
But the best comment yet came from a student who was criticised for his bad language: 'I used bloody and crap as I don't really consider them to be swear words.' I'm sure a lot of people don't but they'll never pass muster for Woman's Weekly. (Or maybe they will nowadays.)