Petra: Get the Three-Day Pass
I had wanted to see Petra for as long as I could remember. Knowing nothing about it, simply did not matter. The best advice is to go very early in the morning when people are at a minimum. You enter through the Siq, a long and narrow rock alley. Take your time and take a deep breath before you get your first look at the Treasury. Soak it in. If you're lucky and there are few others, sit in the ground and just stare.
Then move on and explore the ancient city of Petra. There are few, if any spots you cannot access, no doubt you could spend three days in this UNESCO World Heritage Site. Talk to the vendors selling jewelry, many are original residents of Petra, who only moved out in the last decades.