But don't forget to have fun! The nav bit is the best part of flight training because it will be your first taste of what you can really do with an aeroplane.
Take plenty of pens with you ... you are going to drop at least one. And something I also do is take a wooden pencil with distance markers carved on the side.
Photocopy a drawing of any airport you're flying into. I find it easier to plan the circuit entry on a flat piece of paper than on the small drawing in ERSA.
If you're going to be tracking close to the edge of the chart, make sure you have the adjacent chart with you. There is nothing worse than having a huge feature like a lake just to your left, but it's no good to you because it's not marked on your chart.
And remember, you're probably not lost; it takes an awful stuff-up to get lost (yes, I've done it). You probably just won't be able to pin-point yourself on the map at that time. When that happens, use what you can see outside and try to find it on the map, not the other way around.
Walrus