Dear Mindreko,
From my experience, you must concentrate on the following areas because questions from these areas appear more frequently than others.... Hell, I'll give you an approximate break up of all the areas :D
1. Simple Equations - 2 to 3 questions
2. Ratio, Proportion and Variation - 2 to 3 questions
3. Numbers - 6 to 8 questions
4. Speed, Time and Distance - 4 to 5 questions
5. Rate and Work - 3 to 4 questions
6. Mixtures and Alligations - 2 to 3 questions
7. Geometry - 4 to 6 questions
8. Mensuration - 2 to 3 questions
9. Statistics - 2 to 3 questions
10. Data Interpretation - 3 to 4 questions (this includes questions on venn diagrams)
11. Sequences and Series - 1 to 3 questions
12. Combinatorics - 2 to 4 questions
I hope this will help you evaluate the relative importance of each topic.
Regards,
Entwistle