Hi!!
The confusion still remains: who is your target audience? If it is internal, then give details of your client, the work content, location, duration of assignment, etc. Include pictures of the client site, local snaps (if the work location) to motivate the interested employees.
If it is for your own company, then do the same with details of your own company. The simple rule of the game is: the poster should be eye-catching. The punch line should be in bright red or blue. If possible, the background color should be the corporate color (the color of your logo).
See if this input helps. Do mail me a copy of your final poster at [Login to view].
Regards,
Anand