There are many paths to victory in The Age of Discovery. Players should not ignore the victory points generated by controlling first or second place in colonies in the New World.
The New World colonies are the only elements that score victory points more than once in the game. At the same time it is very difficult to focus solely on a New World Colony strategy.
Other players will recognize this strategy and it will become very difficult to control enough regions to win the game when other players make a concerted effort to confront you in the New World. Spreading your colonists into too many regions can also be dangerous.
A sudden explosion of colonization by several opponents all at once will put you in an impossible position as you try to defend too many places.
Successful players will often use a two-fold strategy to achieve victory.
For example they may focus on controlling one or two regions, take second in one or two more and then work very hard on developing their economies (using the money generated to acquire capital buildings as needed).
Another approach may be to augment a New World strategy by acquiring captains and exploring frequently, using exploration to gain a foothold in the New World. There are many combinations to try. Some will work better than others. As players begin to recognize successful strategies, expect to meet resistance and be prepared to adapt to your opponents.
A note on war as a strategy: in The Age of Discovery, warfare is not a dominant strategy by itself. It is merely a tool to tip the balance in a few key colonies at key moments.