The Phillips is brilliant, but cross-reference it with another guide, preferably one with a different form illustration. Most of the photos are very good in my edition, but there's a great deal of variation in colour etc with some species. Oh, and read the whole book before you even think about eating anything.
You'll enjoy the discussions of toxicity - dwell on the deadliest species at length and savour the stories of lingering and agonising death, as you need them to haunt your dreams and come back to you in a flash. There are two elements to risk - likelihood and severity. Sometimes misidentification can result from from utter cluelessness, and sometimes from missing subtle distinctions, but the common factor in most fatal poisonings is people not really believing that eating a mushroom will kill them. You don't need to know everything, but you need to know how much you know - for example the mushroom that nearly killed Nick Evans and his family belongs to a genus which contains nothing that is worth eating and a few things that will kill you - so you need to be able to recognize the genus to avoid it but don't necessarily need to be able to identify species within it. Practise IDing everything whether it's potentially edible or not, but know what you are looking for. ID stuff in situ. Phillips is good with descriptive sensory stuff, but you should cross that with a systematic approach and eliminate specimens from your enquiries if there's anything about them that contradicts the description. Don't experiment with stuff of disputed or unknown edibility, and don't pick anything that's too young or too old to be able to see its features clearly. Most importantly, don't trust some muppet on the internet...
