I like Math::Random a lot. It can give you random data with a selectable probability distribution.

As for "best practices", try googling the cryptographic literatere for 'prng' (pseudo-random number generat{or,ion}). The ideal thing (modulo techno-paranoia) is a hardware random number generator supported by the kernel. Kernel /dev/urandom is generally good. Non-pseudo generators all rely on some source of well-characterized but unpredictable noise.