Creative collaboration is the practice of making something that neither partner could have made alone, which is a different aspiration than the division of labor — it requires the dissolution, at least temporarily, of the proprietary relationship to one's own ideas. The difficulty of collaboration is not primarily logistical but psychological: the willingness to let the work be changed by another mind in ways you would not have chosen, and to recognize that the work that emerges may be better for it. Trust is the medium collaboration works in, more than any shared aesthetic.
Each step builds on the last.