I saw a really good tutorial on youtube the other day about city placements. The video is specifically about starting locations but I think a lot of it is applicable to all cities. It is kind of long so I'll summarize the main points here, but I recommend watching the whole thing because he explains it much better than I ever could.
- Housing is important. Settling by fresh water (rivers, lakes) is best followed by salt water.
- When you settle on a tile, the minimum yield you get from the city center tile is 2 food, 1 prod. If the tile has any yields beyond that those get added to your city center tile's yield. For example settling on a flatlands plains (1 food, 1 prod) yields 2 food, 1 prod after settling. Settling on a plains hill (1 food, 2 prod) yields 2 food, 2 prod after settling.
- It's generally best to settle on a plains hill or a luxury for the reason above. You get more yields out of your city center tile. Settling on a luxury has the additional bonuses of applying amenities right away, or you can sell it to an AI, and frees up a tile in your city that can be used for districts, wonders, etc.
- Look at the terrain in the first two rings around your city. The third ring takes too long for your borders to expand to so you won't get a lot of value out of those tiles for a long time.
- Hills and forests/rainforest are good for production and chops. Tundra and Desert are really bad because of the lower yields.
Edit:
@Mozzington already posted this video. That's what I get for not reading the thread.