Well, best to avoid touching each other until after you've established that you and your doppleganger are not, in fact, the same person. Blinovitch and all that.

And really, best to avoid speaking even general timelines if you can. Unless you're a time sensitive and have a knack for sorting out the important bits, you'll never really know what you could be changing.

But otherwise, perfectly sensible advice! I particularly enjoy your taste in literary references.