Given your predicament I think you are probably over expanding (which was fine in Civ 1-3, but you can lose the game in Civ 4 - OR, you have not read the civlopedia and are using spearman for defence, ect... therefore some general advice.
On a standard map:
- expand to 6-9 cities max - you don't need ANY more to win.
- focus on a religion early (play as INCA) - go for hinduism
- then focus on brozeworking....
- only build cities close to special resources, try to get 2-4 special resources within your cities FAT cross....
- try to keep cities on coasts/rivers, avoid deserts.
-spread your religion, make friends
- Tech Priority
1. Polytheism (Hinduism)
1. Bronze Working (Chops, Spears/Axes, Copper)
2. Animal Husbandry (Pastures)
3. Pottery (Cottages)
5. Wheel (Roads)
6. Iron Working (Swords, Iron)
7. Metal Casting (Forges)
8. Priesthood (Temples, Oracle)
9. Alphabet (Tech Trades)
10. Code of Laws (Confucisism, Courthouses)
11. Currency (Markets, +1 Trade)
12. Monarchy (Hereditary Rule)
13. Monotheism (Organized Religion Civic, +25% pro)
For general warfare:
stone age: 2 archers/city + some guys to explore
bronze age: 2 archers + 1 axeman/city
late brone age: above + 2 spearman/city; arm of axe (if defensive), swords (if offensive)
middle ages: 2 longbows, 1 cross bows, 2-3 pikeman/city; Army of 10 knights