One technique that's been helpful in our work is to break the processes down into successive levels of detail. Show each level with a reasonable amount of detail. Then, break down any step that doesn't have enough detail into its own diagram.
For example, mapping the process to "Get ready for school" might look like:
Even without going into any more levels of detail, we understand the process at a high level.
But, step 2 may not have enough detail for our needs. So map it out in it's own:
You'll need multiple pages and diagrams, but the goal is to keep the overall diagram sensible. Don't put too many shapes or steps on each page.
The key is to keep each page complete and have an overall meaning, not simply a continuation of a previous page with off-page references.