I am wanting to record sales activities, track, and produce reports for each detail, what is the best way to do that? Would I need to custom program a user defined field for this purpose? Do you have any other suggestions or tips?

Try turning on logging to Journal

File/Preferences/logging and select Both for all the activities you want to track - You need to do this for each user.

All activities are then recorded in the Personal Journal and can be used as the basis of individual weekly/monthly reports to a sales manager etc.