Trying to parse scriptPubKeys and get the individual opcodes. My question is: How would you identify the "bytes to push" values?

Here's an example of the typical scriptPubKey:

  76       A9             14
OP_DUP OP_HASH160    Bytes to push

89 AB CD EF AB BA AB BA AB BA AB BA AB BA AB BA AB BA AB BA   88         AC
                      Data to push                     OP_EQUALVERIFY OP_CHECKSIG

bitcoin.it/wiki

Does "bytes to push" only occur after specific opcodes? Or is it that anything that doesn't correspond to an opcode is interpreted as indicating the upcoming number of bytes to push on to the stack?

Note: Basically any tips/advice on parsing the locking script would be handy.