There isn't an official style document but perlstyle offers some advice on naming conventions, and there are some other conventions:

• Module names are MixedCaseNoUnderscores
• Constants are UPPERCASE_WITH_UNDERSCORES
• Package wide variables are Mixed_Case_With_Underscores
• Function variables are lowercase_with_underscores

Also, function and method names are also lowercase_with_underscore

This isn't complete or in any way authoritive, but in my opinion it's a good start. Take a look at the modules which are in the Perl distribution. They mostly follow the conventions listed above.

TVSET makes some good comments about the readability of your code.

If your code is readable, and you're consistent in whatever naming convention you use, you'll have maintainable code. If you're planning on putting modules on CPAN, then examine some of the more well-known modules (like DBI and LWP) to see what the naming conventions are.

Arjen