I believe there are3 key elements to focus on - (1) updated organizational structure with clear roles, (2) easily accessible and regularly updated information flow on company strategy, targets, activities&events, progress, future, etc. and (3) leaders acting as culture messengers and role models = walk the talk
Culture- 'the way things get done here :) ' .
A Good Culture is said to be 'OCTAPACE' - There should be Openess , Collaboration, Trust, Autonomy, Proactive, Authenticity , Confrontation( healthy) & Experimentation. You need to figure out which of this needs to get improved through structured questionnaires / FGDs/ Townhalls.
Once you understand what needs to be improved get the buy-ins from Leaderships & key Linchpins in the organization & have an interventions to improve the same.
The key is to get the leadership endorse the Culture element and the rest will follow.
Standard culture audit instruments are available in the sites/ T V Rao Learning Systems or let me know , i can send it to you via email.
Remember: It all starts with the Leaders. You would be surprised to see that the score of each element will vary department to department (an ample proof that leaders set the tone)