Several methods I have used successfully:
1) Find a pecan orchard that you can get access to hunt. Crows love pecans and will fly down on the ground to get them. Full camo and an accurate small bore rifle are a must.Best in fall when the nuts begin to fall or after harvest when culls are available.
2)In the spring, around March,locate crow roosts by driving country roads and using a crow call. Once you hear the crows, get in a edgeline with a mod or full choked shotgun and use the assembly call, even the distress call will work. The young crows will keep coming, so be ready!
There are other methods I use such as the all black mojo crow with owl decoy that I custom modify, but that is for advanced shooting!