Configuring the workflow is one of the most complicated tasks in Redmine. Also, proper configuration of issue status transitions is more significant and important than configuration of fields permissions. So before doing this, I would recommend that you draw a diagram of issue status transitions that you plan to implement, and discuss it with your team in detail. In this way, you will minimize the risk of the need to modify the workflow later. However, I believe that you can't fully avoid further modifications, as the workflow should be an adaptive system and can still change.
Modifying the workflow is not so complicated as risky. A wrong configuration can allow more than users need, or limit them when they need more. You have already seen all the configuration forms and the amount of elements in them, so you would probably agree that it's easy to miss something when you add a new role, tracker, or issue status. Therefore, under this section, we will talk about basic principles that you should follow while adding new objects to the workflow.
Member roles can be added using the New role link, which can be found in the contextual menu in the top-right corner of the Roles and permissions page. Clicking on this link opens the following form:
This form also contains Permissions, which I did not include in the screenshot. The same form can be invoked with the Copy link which is located in the rightmost column of the role list.
As you can see, the new role form is very much like the role edit form that was discussed earlier, but with a new Copy workflow from option. This new option allows you to choose the role, the workflow configuration for all trackers (that is, issue status transitions and fields permissions, but not role permissions) of which will be copied into the newly created one.
So, let's compile a list of actions that you should do when creating a new role, to make this process easy and flawless:
A new tracker can be added using the New tracker link. This link is located in the top-right contextual menu of the tracker list that can be found on the Trackers page. It opens the following form:
This form is almost identical to the one which is used for editing trackers. Like the new role form, this form also has the Copy workflow from option, which has exactly the same meaning—if a tracker is selected for this option, the workflow configuration for all roles and the selected tracker will be copied into the new tracker.
So, to avoid mistakes and misconfiguration, try to follow these principles while creating new tracker:
A new issue status can be added using the New status link, which can be found on the Issue statuses page. This link opens the following form:
This form is exactly the same as the one that is used to edit issue statuses. As you can see, no Copy workflow from option is available this time. Adding an issue status is not going to be so easy.
The workflow for issue statuses cannot be just copied, as new statuses are usually placed somewhere between existing ones (for example, New—New status—In Progress). This means that new issue statuses definitely need to be configured manually. In practice, however, users often forget about the need to add the new status to the workflow, which ends up in confusion and a lack of understanding as to why the new issue status is not visible in the issue forms and the workflow. Unfortunately, Redmine's interface and approach to this problem do not help much.
So let's try to define some principles that can help make this process easier: