By Skrealder 08/22/2019
Turn 0. Always upgrade. Usually you get +1, but explorer is strong on tighter maps. Prioritize ruins over cities in the early game. To explore, move your warrior in the direction of the most abundant resources, ideally farms.
Turn 1. (4S) A lot can vary based on the number of farms/resources you have, and how your 2nd looks. Having as much information as possible is crucial to deciding what to do. Move your first warrior before debating the merits of a 2nd warrior. With ruins, you can always get a 2nd warrior. If there is an unnatural abundance of forests, which happens from time to time, don't make a 2nd warrior and prepare to rush forestry/hunting. If you can afford all the tech/city upgrades you need in the upcoming turns, get a 2nd warrior.
Turn 2. (6/8S) If you have ruins, you will get the first one this turn. If you get 3pop or 10S and have at least 3 farms, you can go to city lvl 3 (stars) or 4 (3pop). Note that if you have 5 farms and 10S, you can also reach lvl 4. 5S and Pop Growth are you friends, and a giant next turn if you can.
Turn 3. If you have good farm (configuration)s, grab Construction when it is super cheap. It is a really strong tech that will give you an immense giant factory. (Provided no ruins or crazy farms) Note that on this turn with 2 warriors, you can't upgrade a city and get construction. Do note with 1 warrior you can get construction, and a lvl 2 city/another t1.