Create choices if you don't have any. Hold the line on contracts early and often. Tie implementation assistance to deals and contracts. This will allow more flexibility when bidding. Vendors versus partners.
Partners are expensive.
During implementation, have a project plan but don't let the plan get a life of its own. Don't spend more time on planning than on the work of the project. Be aware of what you are trying to do, by when and with what. The target date is the last thing that slips. Run parallels and compare the old and the new.