They will come to food early, feed and then water. Be there near sun up.
About 2 - 3 p.m. they will return to the field and repeat the process. Water tanks are good in the afternoon to dusk.
See if you can determine how they enter the field, i.e. over a tree or tree line, across a corner or over a barn. A lot of times they will use some sort of structure to enter a field. That's makes for a good spot to sit. They also like power lines, don't shoot the power lines.
And never overlook a dead tree. Dove love to sit in a dead tree. Sit under that tree for some easy pickins.
"Count that day lost whose low, descending sun
Is not, in part, obscured by powder from my gun"