The problem with this question is that it seems to infer that the success of one nation over another was due to the strategies adopted as a result of a conscious choice by various nations. Part of the strength of this work lies in the way that it shows how environmental factors played the key role in determining the success of various nations over another, rather than the specific strategies that were adopted, therefore I would challenge this question.
However, the key factors that Diamond talks about are firstly farming. Diamond gives a convincing explanation of how societies that are based around hunting and gathering are not able to develop in the same way that agricultural societies can. This gives societies an advantage in so many ways over their counterparts who are hunter-gatherers.
Secondly, location is a key factor in terms of the animals that can be domesticated and the advantages that this gives society in terms of the way that agricultural output can be boosted and trade can be utilised. This of course also is linked to the third and perhaps most important point, which is the way in which the domestication of animals exposes people to germs and disease, allowing them to build up a greater resistance and immunity than other nations which have fewer animals.