At my Level 2 KB workshop yesterday in Santa Monica I had my students apply an isometric hold with a bell that they cannot press before pressing a lighter weight. For example, I had a student that cannot press a 70lb bell clean and hold a 70lb kettlebell at the starting position for five second. I told him to crush grip the handle, flex the lat, flex the legs, stomach etc. I told them to avoid trying to press it. I just wanted them to get comfortable with a heavier weight and to learn how to get super tight when pressing heavier weights. I had each person do three isometic holds and then I told them to immediately clean a lighter kettlebell and press it. Everyone noticed that the lighter kettlebell felt much ligher than normal and they were able to press with better technique.
Often people that can press a 70lb bell 6+ times fail to press the 88lb bell bell do to due to lack of confidence. In other words, they clean the bell it feels heavy and they automatically tell themself that they will not be able to press it and sure enough they cannot. They have the strength, but mentally they are not ready. Also, when you lift a lighter bell you do not have to use strict technique. You can get away with not flexing the lat and staying super tight. However, when you try to press an 88lb bell that is not the case.
Doing an isometic hold allows you to work on technique in the starting position which is often where people screw up. To lift a heavy weight, you have to have proper technique without thinking about it. If you have to clean a bell and then think about what to do, you will most likely fail or use crappy form. Imagine a powerlifter that is about to bench press 700lbs. He gets a lift off and then before lowering the weight to his chest, he thinks about getting tight and technique. His chances of pressing the weight just went down dramatically. He should know exactly what to do before he ever gets to the bench.
Try doing some isometric holds with a bell that you cannot press before you next workout. Do three 5 second holds and focus on flexing everything as hard as possible. Then move into your Mil press workout and let me know what happens.