Defining Variables In Separate Module

I started plugging away at VB a little over a month a go and i feel i've learnt alot but can see just how limited my knowledge is. how to define all my variables in one module that then will feed into the code on other modules and forms in the workbook where required. For example, my spreadsheet has approx 30 different variables that are called upon by a variety of subs. How do i define all these in one place and then just call on the relevant ones when required rather then having to redefine them for every new sub.