Best thing to do is get a long handled, fine mesh(1/4") net. when you scoop the net do it hard along the bottom and through all the weeds along the bank. you should come up with a lot of crap in your net. Just dump everything out and pick up your crawfish, minnows, ect.

Do this up and down the bank of a creek, river, pond, ect.
hope this helps....works well in Louisiana.
I just buy 35lbs for $20, i can imagine they are rather price up north.

Good Luck