When you are buying magickal books online or in a bookstore, there are some things you need to keep in mind before buying that book.
The first thing is, Don't Buy The Book Because The Cover Is Artful. I really love books and I adore them, but what I hate most is when they try to hide an awful book with a beautiful cover. I have seen books that look very interesting and when I pop it open it looks like the author only wrote it for the money. I am not saying that all books that look nice on the outside are going to end up awful, but that you need to also look on the inside too and not just the cover. Yes the cover may tell you what the book contains inside with the title, but without a reading the first few pages you may be disappointed when you bring it home and read it.
I understand if it is your first time into the Magickal Arts and you are in a bookstore looking for a good book to learn from. Even if you look into the book you may still not know if it is good or not. My suggestion is to ask some people that are looking at those books and ask which one is good. If you are shy or hiding from your practice than do your shopping online.
The second thing is, Don't Buy The Book Because It Cost So Much. I have seen many online where books may cost 30 to 150 dollars per book. Just because it cost so much doesn't mean it is the best book out there. I have seen a book about Aleister Crowley tenth edition for 80 dollars. Now many of you that are reading will agree on the price but you have to remember, it isn't the ordinal and is the tenth edition. Tenth edition means how many times they changed it by removing information, changing information, updating or down dating, or/and adding what they believe in. Why waste 80 dollars when you can try to find his first real works online or the real thing? Of course if it is the type of book you are searching for then you that is by all means a real reason to get it. But don't go into a bookstore or online and look at their books and want to get a book just because it is costly.
And lastly, Remember The Author. If you bought a book and you loved the handy work inside, remember the author. There are a lot of books out there that hold false information. The reason that is so is because even if magick is an art and a science, it is hard to prove if it is real. I remember when I was first interested into the arts. I was reading a bunch of stuff online, buying books that look like they would help, spoke to a few people on this site, and even trying to practice what I have learn. After so many years I look back and realize I didn't understood the difference between Fairy Land and magick. Back then I really did thought that I you could learn how to bend trees with your mind and thought I can control a rock to do my bidding. There wasn't a line of reality and falsehood for me to see. And that is what some of the authors are going at, writing some stuff and selling it for money. Yeah later on I learned my lesson by talking to people that really know what they are talking about, but if you are only learning from books than around 30% of what you read is really true. This is why you must remember the author if you believe their work is well done. If you are still new, please ask around and do some research on the book before getting it.
Again, I am not saying don't ever get a book. I am saying don't buy the book for the wrong reasons.