Did you know you can manually add a contact at a specific point in your automation?
Just follow these steps:
1. Add a Goal action above the step in the automation that you want the contact to begin at
2. Configure the Goal so that a contact must have the Skip to goal tag to reach the Goal step in the automation:

 
3. Add the Skip to goal tag to your contact
4. Manually add the contact to the automation
Use this simple tactic to test a certain part of an automation, or when you want to add a contact to an automation without going through all the steps.
For more in-depth instruction, watch the video or read the Help article.