Let me start off by saying a merger will take longer than you think. Be prepared to deal with management coming and going throughout the process. You need to lay out the plans for the future and get your staff thinking about the change and whether they want to be part of it. Engage your customers early and communicate with them about the process. Make sure you support the emotional needs of your staff as the transition happens. Oh and don’t underestimate the challenges of merging accounting systems!