OK. So here is my study plan. I passed both Tech and General after about six weeks of study. This was my method:
Watched the license prep videos by Gary Wise and crew (www.w4eey.com). Videos are posted on his website and on his YouTube channel.
I watched many of Dave Casler license prep videos also (https://www.youtube.com/user/davecasler). Dave does a great job on conceptional background for the material. Not essential, but very useful.
Worked my way through the appropriate ARRL license manuals a chapter at a time before I watched the video for that chapter
Used the online flash cards from https://hamexam.org/ and ARRL prep exams. AA9PW.com also has practice exams where you don’t have to log in to take the practice test. Drill, drill, drill!
Also, I downloaded the question pools (in PDF format) from ARRL for each license level. Save these on your computer. They make an excellent index, and I find it helpful to do a quick PDF search for the question and the page location in the manual for quick reference when I need to reread a section. (The indexes in the ARRL manuals are not very good, although the Extra Class index is better, and the numbering system for the questions in the manual is confusing.)
I found some chapter material was easy, others I bogged down and just had to dig in and plow through to get through it. The ARRL manuals are notoriously dull, but they do give the “official” version of what you need to know. I’ve found them useful for reference also after I pass the exam. Or donate them to a fellow ham to encourage them.
My plan for passing Extra is the same, although the question pool is about 750 questions, more than twice the questions for both Tech and General exams combined, so I am allowing about 8 weeks of solid study. Limit yourself to a couple of hours a day, or you will burn out.
Dan Ivey (see the Gary Wise videos) has two really great study videos on the math sections for all three levels of exam. Be sure to download and print off his PDF study handouts for the math equations. He does a superb job of teaching you how to actually do the calculations along with some cheat tips for the more difficult ones.
Finally, make it fun! See some humor in the process. Remember, this is a hobby.
Here’s the link to his math video for the Extra Class .
Hope this helps anyone trying to upgrade!