Share your priorities – make them aware of what your strategic priorities are at the time and if they can help they will. If they can’t help, then let them know what the bigger picture is and maybe they can help down the road.
Let them help you build your internal business case – it’s very common in elearning that the learning and development team will have to “sell” the idea internally in order to get approval for projects so let the vendor help you! It’s only in their best interests.
Act as collaborative partners – once you’ve reached a deal and have that contract signed, work as a team to achieve long-term goals and expectations. This will only pay-off in the long run and if things go awry, you’ve got a partner at the table to support each other.
Be transparent with each other – being able to trust each other will only increase the ease at which the project advances, as well as the overall success. Everyone should understand that the speed of business changes, so as long as everyone is on the same page there shouldn’t be a problem.