Reddit mentions: The best automotive testing & certification books

-Nothing beats hands on experience. If you can get a job working for a repair station, DO IT.
-These pdfs are very useful.
-If you can not get a job, go to your local airfield. NOT the airport. They have security. airfields don't, typically. Go around to the local shops in the area and talk to the owners. Tell them you are wanting to get your A&P and are looking for somewhere to help you get your hands on experience besides the school. Maybe an internship or something to 1) get that foot in the door or 2) AT LEAST know what you are getting yourself into.
-If you are already in a school, hear are some things you are going to need to know:

• Keep your eye on the prize and don't get discouraged.
  
• If you understand something, don't hold the knowledge in. You learn 100% more by helping others understand the material that way.
  
• If you don't understand something, ask questions. Bug the **** out of that instructor. They are there to make you understand it and if they aren't explaining it well enough and are being a dick about it, then /r/aviation is a click away. I would and I'm sure others here would be more than happy to help you understand.
  
• Get Prepware for the writtens. It's actually a great study reference guide. If prepware is too expensive, then just the ASA General, Airframe, and Powerplant books are your best bet. They come with some good Oral questions to study and a Practical guide on what to expect. Prepware is just super useful to help you figure out if you are "test" ready yet. Which brings me to another thing.
  
• When you are mock testing yourself over the writtens. You have an hour on the general, but only 60 questions to take, while airframe and powerplant are two hours and 100 questions a piece. Use a scratch pad. Use it to write down the ones you are unsure about and come back to them once you get through all your questions. The worse feeling is being on a timed test and being stuck on question 10 because you can't remember the damned answer.
  -My last piece of advice is read the FARs! You need to know FAR 1, 3, 21, 23, 25, 35, 39, 43 (and appendix A, B, C, and D), 45, 47, 65, 121, 125, 135, 145, 147. I threw in a couple extras just because I thought they were cool to know. But seriously, you want an A&P certification? One of the only mechanical certifications given out by the federal government? Then read the laws they made for us. Super important.

I like this one. I teach auto mechanics at a technical college, and many of my students have used this study guide successfully. Also, I'd recommend taking one test at first (whichever area you feel strongest in), and study like crazy beforehand. Once you have that one under your belt, you'll be better prepared for the next ones. Good luck!

I bought http://www.amazon.com/gp/product/1428321012/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1, and the practice tests from ASE. The study guides from ASE are free. http://www.freeasestudyguides.com is good too.

Book wise, Factory service manuals will be your bet to what you are looking for as far as details. The down side is that it requires you to already understand some basic automotive systems/fundamentals/tests procedures and theory. For some basic automotive knowledge, you can order the A Series Motorage ASE study guides

https://www.passthease.com/about?cid=95900&gclid=EAIaIQobChMIvZXc8N204wIVl9dkCh1bVA-8EAAYASACEgLDCvD_BwE

Or the Delmar study guide:

Automotive Technician Certification Test Preparation Manual https://www.amazon.com/dp/1428321012/ref=cm_sw_r_cp_api_i_pU0kDb4KB0M73

This is what I bought for the shop probably overkill for 1 person. You might find them at the library though.
https://www.amazon.com/gp/product/1418061395/ref=oh_aui_search_detailpage?ie=UTF8&psc=1