If you put a city on a hill you get +1 production and extra defence. If you put a city beside a river, you can build the water-mill and the garden, which are both very useful buildings, and the river also forms a defensive barrier (provided you put the city on the right side!). If the city is next to a mountain, you can build an observatory, although that's not usually very important, because of the limited importance of self-generated research. Mountains are also useful defensively though. So the ideal situation would be a hill beside a river and a mountain. Possibly you'd also want sea, so you can build ships, although that's a bit of a mixed blessing, as sea tends to reduce the number of tiles which can usefully be worked.
The quickest way to make a resource available is to settle on top of it.