‘Bunch skills’ is a catch-all term that means generally being considerate to the riders around you, but there are two key skills that I’d pay particular attention to.
One key skill is not pushing your rear wheel backwards as you get out of the saddle. The constant accelerations of a race will require you to quickly turn the power on, but practice doing this smoothly when moving from the seated position to standing and back down.
This means your bike will remain in the same place in relation to the riders around you, which is especially important in hillier races where you start climbs in the middle of the bunch. If you fail to do this don’t be surprised if your fellow races get very annoyed when they almost ride into your rear wheel.
Another important bunch skill is to not brake sharply. Practice using the minimum amount of braking possible to avoid the wheel in front when the person in front slows down – you can try this on the club run or chaingang.
If you hit the brakes hard then the person behind will brake even harder and the person behind them even harder again, and so on, with the concertina effect causing all sorts of problems for those towards the back of the bunch.
Practice slowing by stopping pedaling rather than reaching straight for the brake lever. Some people will tell you to use the rear brake so the person behind you can see you are braking, however I would advocate using both brakes lightly as this is a far more controlled way of slowing. Besides, if the person behind you is riding correctly they won’t be looking at your rear brake and therefore won’t see the movement of the caliper anyway.