On bright days, bright colors, on dark or over cast days, and murky water, I use dark purple and or black.
If neither works, I use dynamite.
Just kiddin, I use rote-none fertilizer.
Ok, ok. I start switching out, until I find a color or bait that works. Different depths also, an search the shallows and channels. There are a myriad of things to check, but trial and error eventually pay off.