My keys to achieving crispy fried foods:
1) Invest in a good thermometer to measure/regulate oil temps.
2) Don’t overcrowd your pan or deep fryer. This is the biggest mistake most folks make. Adding more chicken/shrimp etc screws up the oil ambient temperature.
3) For all foods, don’t disturb them while frying!
4) Double dip. Start off with your flour mixture. Then dip into your egg/milk wash. Then dip in your flour mixture.
5) Speaking of flour mixture, my other ingredients vary based upon the taste that I want to achieve, and total cooking time. Shrimp cooks quickly. So, I gravitate towards panko breadcrumbs. Mainly because panko burns easily. Chicken takes longer to fry. Italian seasoned breadcrumbs or corn meal ( or a combo) works well.
I hope that this helps!