I got above 10 in all the categories, but then that's to be expected (I'm a native English speaker with a PhD in English!). Like the above poster, I don't know what advice I can offer, since you've been through it before.
Personally, during my test I was thrown by time - I was determined not to rush, but ended up leaving the test after only about 40 mins, because I did the speaking part last, and then it was all over! I thought I might be able to go back to check answers for the other sections, but that wasn't possible. There was no clock in the room (or I couldn't see one from my allocated desk), and I can't remember if I didn't have a watch on, or if you weren't allowed to bring one into the room with you, but I had no idea what time it was, so had just ploughed through the sections quickly. My advice would definitely be to take your time with the reading and writing! Check your answers before submitting. For listening practice if English isn't your first language, listen to talk radio as much as you can, and of course try to read as much in English as possible (though I would imagine you are doing these things already).
Good luck for your next test.