There’s nothing that works better for getting strong than basic barbell training. Full range of motion lifts that load the entire skeleton are both efficient and effective in producing an adaptation that is beneficial for all aspects of human performance. Whatever it is you do, whether it’s Krav Maga, sports, martial arts, or just life, you need to be stronger to be better at it.
There are always a lot of questions on the squat. As a Starting Strength Coach, I teach the squat as described in Starting Strength: Basic Barbell Training, by Mark Rippetoe. The proper grip is a thumbless grip, with straight wrists. The bar is placed under the traps, on top of the posterior deltoid, under the spine of the scapula. Keeping the chest up and elbows back wedges the bar in place. Don’t neglect setting up properly. Issues with tightness at the bottom of the squat can sometimes be traced to a loose upper back and a crappy grip or bar position.
Here’s a video I put together for Starting Strength. Comment below if you have any questions.