When the water is murky try taking the yarn off. Remember that the fish will see the yarn coming down river and sometimes people use large amounts of yarn completely covering the corky. I have much better luck just using a single or double #12 corky. Red, Orange, Luminous Peach, and green are good colors. Thats only my opinion and I'm sure everyone has there way of fishing. It works for me. Try FRESH eggs, they never fail. Dont forget, you should always have plenty of scents with you.
Mikes Shrimp Oil, Smelly Jelly or an old favorite
WD-40!!! Yes it works