Before you proceed with memorizing individual facts and rules, you need to build an overall picture of the learned knowledge. Only when individual pieces fit to build a single coherent structure, will you be able to dramatically reduce the learning time. This is closely related to the problem comprehension mentioned in Rule 1: Do not learn if you do not understand. A single separated piece of your picture is like a single German word in the textbook of history.

Do not start from memorizing loosely related facts! First read a chapter in your book that puts them together (e.g. the principles of the internal combustion engine). Only then proceed with learning using individual questions and answers (e.g. What moves the pistons in the internal combustion engine?), etc.