• Add something like PHP_CodeSniffer to pre-commit in Subversion to reject code that doesn’t follow standards
• Run tests in a Subversion post-commit script
• Try to switch to git, because you can also do commits when offline

Sadly, there were also less good ideas like

• Prefix private/protected class methods and properties with an underscore (makes refactoring very difficult; instead you should start with all properties being protected anyway and only make properties public, that need to be public)
• Limit line length to 85 chars (120 chars are ok – nobody uses a 80 char text console for coding anymore – wide screens are standard, even for developers)
• Use PHP_CodeSniffer (I like ZendCodeAnalyzer)

Look at this, if you wanna see bad practices: