Well, the most important thing is to make sure people can successfully build things. Next most important is to minimize the manual intervention required (and the degree to which that manual intervention is spread out through time).
Getting all the necessary 3rd party libraries *for this package and all dependencies* is a good start. Including, somehow, required utilities would also be worthwhile. Being able to automate all of that, appropriate to distro and project, would be optimal (but potentially more work than it's worth, depending).