With horses that like to curl their neck and become over bent, the rider needs to be careful not to get their reins too short. This will cause the horse to stay too short in the neck. Think of having longer arms that are always reaching towards the horse’s mouth.
You have to have the ability to ride in "neutral", with no aids whatsoever, for your horse to be able to feel, recognize, and respond to your lightest of aids.
Allow with the reins when approaching a drop into water. Holding too much in the last strides can cause the horse to not use his body fully over the fence into the water - which can cause a stumble or fall on landing in the water.
"Effective aids are not exhausting to the rider and not souring to the horse." ~ Charles de Kunffy
The sign of a good rider is that their aids are so subtle and smooth that you can hardly see what they are doing.