So IMO following should be taken care of before starting the project:
- Have the project lead on board: You may want to move someone from other project or share somebodies time to minimize the cost but that comes with trouble. The project lead should be able to propare himself to spend significant amount of time on the project.
- Project ramp-up plan: At the time of agreement itself, propose a very high level project ram-up plan to set the client's expectation right. Ramp-up plan should have time allocated for understanding the existing system, requirements/expectation, team building, trails and making a plan for actual project execution. Remember that people at client's end know much more about their product/work and unless explicitly stated, they will not understand (or be willing to understand) the time taken in above mentioned activities. This plan should be made by the project manager (who is talking to client initially) along with project lead and project lead should start working on this plan.
- Do not club the project with other project: Unless the project is really being managed in a clubbed manner at client's end also, you should not try to club the project with other at your end for ease of management. you can always do this later when the project is running smoothly. In initial phase, project requires a lot of attention and hence has to be handled separately.
- Assemble initial team quickly: Quickly get at least one person in each function that you are starting the project so that the initial work can be shown asap. The project lead has to identify these functions and has to prepare a very high level plan (may be shared with the client if required) for each function to start. These team members are required to understand actual work, try it and start planning for execution.