Different people learn differently, and different instructors teach differently, and when student and CFI differences clash, your training will probably not go well. If you can't understand a prospective CFI's answers to your questions, and the CFI can't reword answers so you do understand, you will likely have similar problems in training. If the two of you can communicate clearly, take an introductory flight lesson to see how you get along in the airplane. In the end, only time will validate your CFI selection. But if your CFI isn't working out, don't be afraid to change.
Flight training is divided into two parts, ground school and flight training.
You have several ground school options. You can attend a scheduled classroom course that may be held at a flight school, independent ground school, high school, or community college. There are also intense, weekend-long ground schools. Or you can take a home-study course, which is composed of videotapes and may include computerized test preparation software. Regardless of the option you chose, you'll need an instructor's endorsement to take the knowledge test.