As kenn3th has mentioned, library books should be sufficient to
provide beginners a good start. At least for me. I would recommend
reading not just one but at least a few books on the basics of PHP
programming as each presents a different way of approaching the
language, thus strengthening your foundations which will be
required when you go for the advanced stuff. Just that it can be
really boring at times if they happen to repeat the same thing in
the same way.
Don't bother remembering function names and stuff. As Albert
Einstein has said, "Never memorize something that you can look up".
Not sure of anything, just look for it in its online manual. Unless
you're planning to go for certification, you'll only need to know
the basics such as the language syntax and the basic language
constructs in order to write PHP scripts. In fact, it is this
simplicity and the completedness of its online manual that makes
PHP so popular among web programming languages. Besides, if you
need more help, the doors of Google and sgForums are always open
for you.
And most importantly, keep that zest to learn PHP going. Without
that, you'll probably give up learning PHP before reaching the fun
part of it. While learning, tell yourself what do you plan to do
with the programming skills you are going to have. And right before
you know it, you might be able to speak in PHP better than in your
mother tongue language. 
