A book on art cant describe what YOU perceive in colors, or how certain compositions will make YOU feel, but it can give you techniques for producing forms and mixing colors which are highly effective, it can inform you of generally true effects which colors and compositions produce on the human mind.
You can decide for yourself whether you want to make use of any of the techniques, but generally speaking, just having them available to experiment with can greatly advance your progress.
This is what got me started, written from a Hermetic perspective focused on the classical Elements.
The theory section is extremely extensive, but again, it is from a Hermetic perspective so if that's not your bag, may not be for you. Exercises are simple, straight forward and effective.
The author does quote the christian bible in places, but that is by way of offering examples, it doesn't require any belief in that direction, if anything I believe he wrote it this way to demonstrate to Christians how their religion is not incompatible with magic.
Thank you for the replies everyone. Magister I have that book and it is fantastic, very comprehensive and easy to understand. Micky - I haven't come across that book but I will check it out, thank you!
The book is actually for a mate who has started dabbling and does not seem to have a lot of knowledge about the subject. For various reasons I can't/don't want to help her with this stuff myself. So I thought books would be the best way to go. I understand your point of view when some of you are saying that you can not truly learn unless you experience something yourself, but there is also no harm in arming yourself with knowledge and learning from other people's experiences as written in books. If you are on a solitary path with no mentors I think it would be very unwise to start dabbling without a bit of research beforehand.
I am going to lend my copy of A Witches Bible and I've also ordered a copy of Spiritual Protection : A Safety Manual for Energy Workers, Healers and Psychics by Sophie Reichter and will check out that book that you mentioned too Micky. That should be a pretty comprehensive bundle and should keep her going for a while!