Also, remove water sources, maybe put some mothballs around your house (probably more of an old-wives tale, but may keep food snakes are looking for away), seal any gaps or holes in house or ground (i.e. any nook or cranny a snake could hide in).
When we used to do reptile surveys, we'd use 1' metal flashing to direct the snakes into buckets we had put in the ground.. maybe use this idea along a fence?
Honestly, I'd be more worried over rodents than snakes.