Custom fit plugs with muffs over them, will give you the highest protection. Custom fit meaning the plugs are molded to the shape of your ear canals.
I use these : Howard Leight MaxLite UF Foam Ear Plugs (NRR 30) - Industrial Uncorded Foam Ear Plugs
There are other plugs with a higher NRR (up to 33) but these are the ones that seal the best in my ears. A higher NRR does no good if they don't seal well.
With Peltor Tac 6 low profile electronic muffs.