What one thing should I help my child improve and work on?

[Creampancakes]

Support Homework Expectations. ...
Send Your Child to School Ready to Learn. ...
Teach Organizational Skills. ...
Teach Study Skills. ...
Know the Disciplinary Policies

I don't understand. Can you elaborate a bit op? It will surely depend on your child?

It also depends on how old they are as different things are more important at different ages?

Why one thing? Why a child knowing discipline policies?! Bizarre.

The very best thing a parent can do is to read stories and share books with their kids every day. So much follows from that. That's the most important advice I can give.

handwriting is a useful skill.

The very best thing a parent can do is to read stories and share books with their kids every day. So much follows from that. That's the most important advice I can give.

^^ this and once they can read by themselves let them read out to you rather than you doing the reading. Audio books are also very helpful with pronunciation.

Read to and with your child and talk to them about what they’ve read.

Not sure exactly what you mean tbh. If you have a child who will be starting in reception next year, I would suggest firstly, make sure they know how to use the toilet properly including hand washing. Teach them how to remove and replace their coat and shoes ( saves TA a lot of time). Teach mealtime etiquette such as using cutlery eating with mouth closed. Teach them to blow their nose. Patience and turn taking and sharing. Oh and try to read to and with them as much as you can

Support Homework Expectations. …

No, if I don't agree with the schools homework expectations, I won't support them, if the school has unreasonable ideas, it's not for me to support them.

Send Your Child to School Ready to Learn. …

I don't even know what this means, human children are pretty much ready to learn all the time, they may not want to learn what the teachers want to teach, but I don't understand what it is I can do to prepare it?

Teach Organizational Skills. …
Teach Study Skills. …
Know the Disciplinary Policies

These seem to be very school based jobs, not parental ones, the other advice seems much more reasonable to me (reading and talking to your child about stuff) I'd also add physical literacy as that's also something that can be mostly done before school begins and continues throughout live.

Vocabulary, teach them lots and lots of words. The best way to do this is through reading, as much as you can. Surround them with a wide range of books that they can pick up and browse, read stories to them, tell them stories about yourself and your own childhood. Talk to interesting people, watch and discuss interesting programmes. And read.

Hi OP, lots of reading or being read to. Whether it be comics, books , labels on tins , absolutely anything. As PP lots of vocabulary. Try at least 10 mins a day if possible 30 mins. Just make sure your child enjoys it!

Reading is super important.

But there's research coming through about the importance of vocabulary which interests me hugely. I'll try not to bore you with the details but basically some children come to school with a vocab based around yes/no and instruction words and some come to school with higher level vocab and are able to describe things/their feelings etc. A teacher would feasibility have to teach a lower vocab child 20 to 30 new words a day to bridge that gap which is obviously almost impossible. Apparently by age 8 the children with a lower vocab are more likely to be working below age related expectations, then go on to perform worse at secondary school and as an adult more likely to be unemployed and/or suffering from poor mental health.

This is obviously a hugely simplistic explanation of some pretty complex data, but basically read to your kid, talk to your kid about everything and let your kid talk.