Easiest way I've found is to hit the ground running. Come up with a very simple project and do it. For example, create a php script that will simply state the following: Hello! Your ip address: {IP} Your operating system: {OS} Your web browser: {Broswer} Your internet service provider: {ISP} Code (markup): Change everything in the { } to actual dynamic data. A beginner could learn to do this in about 5-6 lines of code, and it will teach you the basics of how PHP works. An experienced PHPer will do it in 1 line of code. Use php.net and read up on how $_SERVER works to display the data to get you started. Once you've done that, expand it to show other neat stuff.
Using http://www.w3schools.com and the main site itself http://www.php.net and practice, practice and practice
The best way to learn PHP its having this CHM file close to you. http://www.php.net/download-docs.php
I used w3schools, then tried to make my own script. Whenever I ran in to a problem, I did a google search for how to do it, or looked at a script that I knew already did what I wanted. If I had any more questions, I did a google search for the command the script was using.
Well i downloaded php triad and I am trying to read this book: php examples..it is simple but need to read this first before going top more advanced things.
I learnt just reading when i need something specific, this is NOT the proper way. But i have been a programmer for over 15 years. Just try to be methodic, learn control structures, I/O functions, String manipulation, just as you'd do with every other language, You better read about object oriented programming cause php frameworks works that way (cakephp, symfony, etc)
I agree with pachecus. PHP manual is good enough for starter, and also look into some sample code that you can found easily
start from basic like add edit delete search uploading database connection etc then try to merge all basic script and make small project ...... if you need help check php forums
What about this book I found PHP_BY_EXAMPLES..I have read about 150 pages now and got lots of concepts clear..though did not start on MYSQL.