Snakes have to have these 3 things in this order to survive.
1-Shelter
2-water
3-a food source
There is of course oxygen too but that's pretty easy to find anywhere.
Look for ground cover near a water source. Water and cover also attracts prey so the food source is often covered by default. Old fallen barns are often not far from a stream or farm pond. Any old stash of grain or corn left behind will of course attract mice and rats and be a perfect herping spot.
Baiting the field is a pretty common method. Find old sheets of tin and plywood or places that look like should be a good spot and dump soiled, smelly shavings from rat and mouse cages underneith. Check back regularly.
Road cruising down quite roads through rural areas just before and right after dark is probably the most effective and lucrative herping...and you have A/C and music. Just cruise around at 5-10 mph and use that eagle eye. Snakes are attracted to the roads to catch the last of the sun's rays and to the retained warmth of asphalt once the sun is gone for the day.
I get yelled at a lot for herping in flipflops and shorts so someone else probably better tell you what's best to wear
