Do not make the mistake of always practicing over perfect distances at home. Sometimes practice meeting a jump on a half stride on purpose... and learn to do it well. This will make you and your horse a safe pair out on cross country.
"Suppleness means that the muscles contract and de-contract, and this has to go through the entire horse, it cannot be blocked in the middle of the back, and it also has to go through the rider." ~ Susanne Miesner
"The less we do on cross country, the easier we are on our horses. Learn how to be more still. Don't touch their mouth unless you need to. Plan your turns." ~ William fox Pitt
Impress your Dressage judges by showing a clear difference between riding a corner and part of a circle.
"The rider's seat is a 'transformer' whose role is to modify the energy emitting from the horse's haunches." ~ Charles de Kunffy