The Greeks colonized for several reasons. Some of these included a fear of overpopulation, a lack of arable land in mainland Greece, and the economic expansion of Greece in the revival following the bronze age collapse. Some of these colonies were set up specifically as trading outposts and were manned by commercially interested settlers. Several of these outposts were set up in places where the Greeks could easily trade with civilizations who possessed goods that were difficult to procure in mainland Greece such as metal.

Colonists were sent out from a mother city(metropolis). The colonists were usually only male, and as a result of this wives had to either be taken from locals by force, or traded for. Cities which were founded were independent, but were meant to maintain economic ties to the metropolis. These cities were initially led by a founder(ktistes). His job was to divide up the land of the newly formed colony. In some cases, criminals and undesirables were forced to found a colony in order to rid the metropolis of them. In other cases, due to extreme overpopulation and scarcity of land even young men could be forced to join a colony and were not allowed back into the Metropolis for a certain amount of time and sometimes people would just volunteer to start a new life.

This is honestly all that I know. Sorry for not being able to directly answer your question.

The first idea behind a colony is to avoid overpopulation. Greece is not a fertile country the political fragmentation means that the territory available to extract ressource was quite limited. Some like Sparta answered this by conquering their neighbours but another solution was to gather volunteers (normally only men), put them on a ship and sail to a land that was said to be able to support a new city. This process was of course planned, the oracle of Delphi played a key role in the process as citizens of the new city would come back to the temple of Apollo to thank the god. The priests would gather informations at the same time.