Tips to prevent your form hijacking in PHP
Here are some tips which prevent form hijacking in PHP.
1) Make register_globals to off to prevent Form Injection with malicious data.
2) Set Error_reporting to E_ALL so that all variables will be intialized before using them.
3) Practice of using htmlentities(), strip_tags(), utf8_decode() and addslashes()A for filtering malicious data in php
4) Make practice of using mysql_escape_string() in mysql.