First, I suggest moving up. Chieftain is fine for learning where all the buttons are, but the AI suffers heavy build penalties at that level. That means that it can't expand well, can't build much military, and won't have much to trade. IOW, that slows down the tech pace for the whole world.
Second, some of the early build questions will be related to your chosen victory condition. If you want a cultural victory, you may want some early temples. If you want a military victory, you don't.
Early builds include:
1) a warrior (or scout) or two for scouting the land -- you need to know where to send the next settler & you need to make contacts;
2) a curragh for scouting;
3) workers & settlers.
How many settlers? I expand until I run out of room, then go make some room.
How many cities? See above.
Science? See other thread.