Finding the right function modules

Hi,

When writing ABAP code, I try to utilize the existing function modules as much as possible.

My problem is - how can I locate these function modules? I guess there are several thousands function modules available, and finding the right one - using the Repository Information System (SE84), for example - takes lot of time.

If you need a function module - where do you start? Also, how do you know whether a function module you need does exist at all?

Regards, Jarmo