We've been doing handwriting OT (or hot housing, depending on whether you speak to the OT or the school) for my 6yr old all year. I find it makes a huge difference to mix up what we are doing:

sometimes we are writing the alphabet (teacher insists that being able to write it upper and lower case at speed is important for automaticity),

sometimes writing "The quick brown fox jumps over the lazy dog" (the whole alphabet but out of order).

sometimes she writes from memory, some times she copies.

some times she's working on her dotted thirds paper focusing purely on neatness, sometimes she's writing on a single sheet over a towel and working on pressure control (neatness goes out the window).

Once she started ADHD medication it started being possible for her to compose for herself so somedays she does that, the next day I get her to copy my re-written version of her paragraph which has the spelling corrected.

sometimes we doing spelling lists.

I never through to try CCN's approach, which is great, but certainly she would have gone mad and been completely non compliant without some variety.

There has been a significant shift through the year from copying to actually writing, from struggling with forming the letters to thinking about spelling/composing.

We have huge pencil grips to correct her grip, we also had a brace for the first half of the year.

We use dotted thirds paper (which our school does not use or encourage)

We use mechanical pencils to teach pressure control

Then mechanical pencil on a single sheet of paper over a towel, to REALLY teach pressure control...

The better all this has made her handwriting the more she is able to use her brain for the writing... Also the ADHD medication has a profound impact on both handwriting and writing.

10 mins a day at home working on the handwriting with me has been possibly the single most important educational experience she has had this year and I think she would have made zero progress at school without my intervention.