The first thing to get right is what goes in your bag. Pack light. Then take out half of what you packed.
This is not advice to ignore. Every experienced traveler says it, and nearly every traveler ignores it the first time, and most of them never ignore it again. A bag you can carry onto a plane, store under your seat, and walk with for thirty minutes without stopping is worth more than a full wardrobe. You will find laundry facilities everywhere you go. You will not regret traveling light.
I travel with an Osprey daypack as my main bag. Everything I need for a three-week trip fits inside it. The camera takes up a third of the space and earns every inch.
At the destination
Arrive in the morning if you can. It gives you the rest of the day to get oriented before you have to sleep somewhere. The first afternoon is for walking, not for logistics.
Eat local food from the start. This is not a health recommendation, it is a practical one. Street food and market food in Asia and much of South America is fresher, cheaper, and more interesting than anything served in a hotel restaurant. The places with plastic chairs and handwritten menus are usually the ones worth going back to.
Get up early. The best light for photography is the hour after sunrise, and the same hour produces the best version of most cities: the markets are active, the traffic has not yet started, and the streets belong to the people who actually live there. Sleeping in is a reliable way to see a city at its worst.
Staying flexible
Do not fill every day. Build in time to slow down, to sit somewhere and watch what happens, to follow an unexpected thread. A trip with every hour accounted for is a different kind of exhausting, and you will miss the things that were not in the plan.
Keep a rough note of what you spent each day. Not a full accounting, just a running number. It tells you when the trip is going off-budget before the problem gets large.
Finally: do not wait until everything is perfect before you go. The bag will never be packed quite right, the flights will never be quite timed correctly, and the weather will not fully cooperate. None of that matters. The trip starts when you decide to take it.