One of the pillars of the sport, pace notes, are to a driver like the bible to a priest. Many underestimate their importance.
A WRC event comprises of roughly 350 km of special stages with, on average, close to 2.000 different corners, of which a large bunch are blind. A top driver knows and will take every single one of those corners on the edge as if he had driven it a hundred times before. The catch is he maybe hasn't done it before, or chances are he doesn't remember what's behind a given bend.
He trusts his notes, and floors it. If the notes are "300 crest flat, on right, for drift L6". He will present his car on the right edge of the crest, flick the car in a drift as he comes, and be pointing the right way for that flat out bend in 6th gear. All that without seeing it, remembering it, without lifting, without fear, and no doubts, ever.
Here are some universal things that you must think of as you make your notes:
1. Know your car.
You must know exactly what your rally car can do, or can't do. It is very difficult to imagine how your car will react on the terrain, as the recce speeds are always limited to speeds varying from 60 to 90kph. There are jumps, ditches, compressions, rocks and all sorts of things that can come into play at or over certain speeds that you can't see on recce. So know your car and learn the ability to project yourself at speed on the stage as you recce it. For this point alone, a pre-event test with the rally car is crucial and it is one of the main problems of privateers. Official drivers have the advantage of systematically getting pre-event time, somewhere, on similar terrain to the upcoming rally. The pre-event test helps, especially after a different surface event.
A mistake in the notes, even if it doesn't throw you off the road, can have catastrophic consequences to your confidence. In top level rallying, you need to be "balls to the wall" from 1st corner to last corner. If a mistake in your notes makes you doubt their accuracy as you're driving, your confidence can quickly fade and so will your stage time.
Don't start improvising in the middle of a recce. Get your system sorted out, then start recceing. Don't start calling similar corners differently as the stage changes it's character. Your system must be consistent and must work on any rallies of the championship. Your confidence depends on it.
Focus on the important stuff. The recce speed can give you a false sense to add a lot of unnecessary detail. Remember that you will be flying through it with the rally car.
5. Mark every corner.
Don't think: "I can see it so no need to mention it". Your co-driver needs to follow, he is not looking out like you are, he is feeling the road through his bottoms. Oh, you need to be sure you don't get confused as well. Your gravel crew, as well, need to follow as they work often in the dark. Just mark the corners and avoid any possibility of confusion. At the speeds you're going, one hesitation and you're out.
6. Get the flow.
Ok this is a difficult one but some stages have a flow in them and I found out that, with care, I could get my notes to represent this flow and keep me in it better. Up to you to see if that's relevant for you or not.
7. Make notes with rythm.
Stages have rythms, that change all the time. A good co-driver will "sing" the notes to you and give a feel for that rythm. You, as a driver, will feel this rythm and react to it. It will also prevent you from falling "asleep". You don't want to lose your attention to the co-driver's speech.
8. Make seperate fog notes.
If you feel the need, make separate fog notes for long straights where there is a high probability of fog for the rally. Your co-driver will read them only if foggy. I made seperate fog notes for the Rhondda stage in 2003. Every time there was an open, no forest stretch, instead of, for example,"1.000 meters" I marked every little thing one could spot. It looked like this: "100 into fence on left into 200 stick on right into 100 big bush on left....into big fence on left immediate hard braking and 150 turn short left 93...."
I was in a fight with a Swede driving a Corolla WRC that year. We came to that stage first thing in the morning and, of course, it was foggy. The fog notes were used and we took a bunch of time out of him in that one. The notes definitely helped me there.
9. Take your time.
Many young drivers show up on WRC recces, see the top drivers blitz through the stages in no time, and try to keep up with them!!! I don't know about others but as far as I am concerned the race is after the recce, not during it. Take your time, doing the stages 20 kph faster and missing important information cause you didn't notice it won't help you. Don't forget other drivers have probably driven those stages before.
10. Use video.
I did not. It was a mistake. Video can help you correct notes you missed and visualize the stage better.
11. Make stage descriptions.
Make a stage description for every stage. This will be read by the co-driver prior to the start and help you focus on, for example, particular dangers.
12. Pay attention to surface changes.
This will help you with managing your tires, and adjusting your driving style. Some stages need to be driven a certain way so as not to wear your rubber out excessively. If some sections need particular care, make note of that in your stage description.