Consider making a simple start by selecting a small map, as this will allow you to play in a confined space while having fewer opponents in the game. To take further advantage, you can consider creating a Archipelago map, in which you will have a bunch of small islands. This will help you in a way that your enemies will have to build ships in a bid to attack you. This takes some time to build ships and you can prepare your army.
You should always try to pick a good spot for your city to be built on. Usually, the game offer suggestions about good spots with blue circles on the map. However, you should still check to avoid any mountains near your city and there should be an abundance of resources in the region.
Consider building a worker first, as they will build roads, which your units can use to move faster. Also, the workers can make trade routes for caravans and land improvements to increase your city’s productivity.
Defend all your cities on the map. For that purpose, you can station at least one military unit in each city. Here, archers can work well to defend the city from a distance. However, you can choose to use any other unit as well for any city.
Choose a research path for victory. There are different ways to win in Civilization IV. You can defeat all your opponents using your military forces or you can also enjoy a technological victory by blasting off to Alpha Centauri.
Consider talking to neighbours and make them friends. You should not only focus on getting involved in war with other cities. In fact, you can also try to make friends with them and then group together to defeat your common enemies.