Does anyone have suggestions on how to use global vars and perl modules.

Yes, as a general rule: don't.

I realize I can pass the vars to the subs, or just keep the code in the script (via subs)

That's the way to go!

I am using quite a few vars.

Depending on how much 'quite' is, and what the subs do, it may be a sign you need a different breakdown in subs. Or that you need to pass around structures (hashes, arrays, objects, references...) instead.

the code is being re-used quite often.

All the more reason to not use global variables to pass parameters around.

Abigail