Vocabulary which is essential for the VR paper is one of the most difficult areas to improve. Encouraging reading, word games and a dictionary are a good place to start. I would also recommend thoroughly learning the times tables for fast recall. This will help with the VR and the Maths.
This is great advice. I'd also suggest a tutor if you can afford it. We've had one this year and last who teaches in a group rather than individually which we like.
Also stay calm and try not to put pressure on the child. The kid will also feel any stress you have about it.
We had one son "pass" and go to Crossley Heath from last year's exam and one son sitting it this year with good pre-test results, so I feel your anxieties, but remember it's not the end of the world if they don't make it.