Reading the rules is no different than reading the assembly instruction manual on your kid’s new 10-speed bike, or your new 6-burner gas grill, or that new desk for your wife’s office. When you get through, and the gears don’t shift, the burners don’t light, and the right side of the desk should be the left side, you finally decide to read the manual. “Oh. I didn’t realize that I needed to (align the gears) (remove the gas seal) (look for the R or L marks on the parts).” At least in the cases of a bike, a grill, or a desk, you can usually go back, read the manual, and fix the errors before they become a safety problem, or cause irreparable damage.
In the case of rules, we don’t often get the chance to fix our screw-ups, so we must read the manual first. In real time, we must know the rules - the language, the purpose, and the implementation of the rules. There is no short cut. You simply must read, and know, the rules as they are written. Period. It is impossible to make rulings on the field without knowing the rules thoroughly - the language, the purpose, the interpretations, and the application of all rules.
Self study by reading the rules, interpretations, and bulletins is a must, and the first step - an ongoing step, but the first step. The next steps, in no particular order, are collaboration with fellow officials, attendance at rules clinics and meetings, completion of rules exams and understanding errors, participation on officiating chat sites, and getting as much on-field experience as possible (especially with scrimmages, where screw-ups won’t be as damaging as in true competition).
The importance of knowing the rules correctly and thoroughly can not be over-stated or over-emphasized.
Good luck!