What should be included on the invitation:

The name of the person hosting the shower

The time, date, and location

RSVP info, including the date you wish to receive RSVPs by

Any theme information if it will require something unique from the average bridal shower (ex: if you want everyone to come dressed in their Halloween costumes, etc)

What shouldn't be included on the invitation:

Gift registry information or request for cash

Suggestions on amounts to spend on gift