How is one to know in what area to build a colony?
What should one look for in building?
Does proximity to the solar system's sun or the planet's size have an effect on productivity of mines?
Should colonies be close together or should they be spread out over several galaxies?
How fast should colonies be built? Should someone build up a colony before settling another or should they be built one right after the other?

Thank you for your coming responses.

well the only answer i got for this one is that yes they shounld be close to each other as possible so you can get your fleets there in case of attack

This all depends upon your playing style and how much time you devote to the game.

While putting many of your colonies together in the same system makes it easier for defense, it also makes it easier for an attacker to find, probe and attack many of your planets at once.

Proximity to the sun (slot 1 is closer than slot 15) affects the productivity of solar satellites and deuterium synthesizers. Solar satellites produce more power in the lower slots. Deuterium synthesizers produce more deuterium in the higher slots.

Timing of colony settlement may depend on your ability to defend each new colony.

Thank you for your help. I didn't want to make some big costly mistake just as I start to expand. This is god information.