Snakes aren't going to go out of their way to find you or your horse. The only problem you have with them is when you take them by surprise and when you feel threatened by either you or your horse. If you leave them alone, you'll be fine. Having said that, you still have to take a few, simple precautionary measures.
Always carry a mobile phone with you when out riding or walking out in a remote location. If you have to go and catch your horse from the back paddocks, take it with you.
Wear sensible shoes and clothing. Going barefoot through long grass is a no-no. Just like when you're riding, we want to see good solid boots on those feet
Arrange to have paths mown through your paddocks particularly in areas with long grass. It's much safer to ride on tracks than go bush bashing though knee high grass.
Be prepared, just in case. Have a first aid kit with appropriate equipment in case of snakebite, for you and your horse.
Keep your stables clean and tidy. Keeping areas well kept and mown will discourage snakes from coming close to any sheds/stables you may use. Try to keep your mice and rat population down, as rodents may attract hungry snakes.
Always inspect objects before picking them up in the paddock and around the stables. Snakes may have found hiding spots in hollow logs, or under woodpiles, and disturbing a snake is not so much of a good idea.
When out walking/riding in paddocks watch where you're going, Check the other side of logs before jumping them or walking over them, and keep your wits about you.
Make everyone aware of the danger Print a safety list, and stick it up in the tack room. Make everyone aware of what needs to be done to have a hassle free summer.