8. If You're Caught Hiding Under A Strange Child's Bed, Just Terrify Them Until They Promise Never To Tell Anyone
Again, it cannot be stressed enough that any legal repercussions of actually following any of this advice is entirely your own lookout. Having travelled back into the past of Gallifrey (despite being told repeatedly that that was impossible) and back into the Doctor's personal timeline (despite being told repeatedly that that was both impossible and a Very Bad Idea), Clara finds herself playing the role of 'Monster Under the Bed' to a young and terrified Doctor. The implication here is that this act scarred the Doctor for life thus causing the entire storyline to happen hundreds of subjective years later, so causality is more or less satisfied. Additionally, she gives the First Doctor one of his very first platitudes (Fear makes companions of all of us), so that's a plus. The addendum to this rule, given immediately afterwards, is of course that if a friend is acting suspiciously, it's probably best to just not ask any followup questions. You have been warned.