Import order of the application

The only time I have received an error importing the zip file is when there are security groups missing or a change to the application that has not been processed correctly eg an entity has been removed but it's still assigned to a workflow. Are you loading the zip into a different environment? 

To answer your question though. There are 16 steps and the order is as follows:

1. Application Security Roles
2. Application Properties
3. Workflow Channels
4. Metadata
5. Cube Views
6. Data Management
7. Task Scheduler
8. Application Dashboards
9. Confirmation Rules
10. Certification Questions
11. Transformation Rules
12. Data Sources
13. Form Templates
14. Journal Templates
15. Workflow Profiles
16. Extensibility Rules

The only thing to add to that list would be that FX rates need to be loaded first, before app zip and/or other XML.  Because if you have add new FX rate tables, they need to go in first, before metadata references to them.

To add to this, OS always imports the XML files in the correct order if you zip them. What error are you receiving? If you are zipping the files, it is likely not a file order loading issue.