Mr. Walis, what the ** are you doing in my forum? LOL, jk
Anyhow, thee Malpine is right on, getting something new as you can is your best bet. But also, make sure that you can use what you learn. For example, if you have a server that has PHP 5 and MySQL 5, then get a book on it because using mysqli and transactions is fantastic.
Also, use PHP.net's manual and read all the comments by users for each function because they are extremely helpful.
edit: yay, this response made me a 4-star'