 1. Observe. Don't interact unless you absolutely must. You're the SCP in this scenario, and the more differences there are between our world and whatever world you're going to, you're going to stick out worse than a Jack Bright Christmas party. We don't want that. 2. Pack light. Keep on your toes, document everything, and remember where the exit is. 3. If it's dangerous or pointless enough that there's no sense in authorizing a follow-up expedition, then don't. Just because you might have D-Class at your disposal does not mean that you have some sort of quota. 4. If there's something dangerous enough to bleed over and mess up our universe, close the door behind you, or even better, destroy it.