It's really all about rehearsing the problem sets. Practice makes perfect and don't panic. The free Maths and English courses on Seneca are specifically designed for the 11 plus exam. By using the courses you can quickly identify the weakest areas of your child and practice those topics more often. You can either do this on Seneca or use additional practice material such as paper revision guides.
The benefit of Seneca is that it covers all the 11+ topics in a highly engaging way. As a result your child will be more motivated to go through the material. it's truly a completely different experience than reading guides and might just be the advantage that your pupil needs.
To summarise the main points:
1. Don't panic
2. Practice makes perfect
3. Do your research to know what to study per school and when the exam is
4. Make a customised revision plan and stick to it
Why not give the 11+ courses a go? There're for free!