Fishing for herring is super simple!
NJ laws states that in 2011 you can take 10 herring per man.
The best area on the Delaware is from Bordentown to above Trenton. Use your fish finder to locate the schools, (witch are more times than not on the channel edge drop offs). Then take a sibiki rig (size 8 hooks) and just jig on the bottom till you hook them.
If you are going to use them for bait DO NOT touch them, use a dehooker tool, stripers can be so picky if they are missing scales they won't touch them! To put them on your hook wet hands and be as gentle as possible. As for time, end of March threw May is best. Hope this helps.