Newbie has questions!

[doctahg]

Hi everyone,
I'm new to this sort of game so had a few questions...Everyone says populate your own galaxy as much as possible...since there's only 1 oxygen planet should I research Gas and ice colonization first? These take forever! I'm totally lost on research..I understand it BUT I have no clue where to start. I read a FAQ, but it's all encompassing and it doesn't really help with the first 50 or so turns. SHould I populate mining colonies with more people? Does that do anything? I thought settling on a nonoxygen colony is under a dome? DO you need to research the gas/ise first for this to work? and so on...a few pointers would be helpful!
Thanks for any help!
Doc