If you are interested in how to colonized in outer space with current technology, and what will actually take to go there,
Robert Zubrin wrote several books about how we could get there cheap and efficient with resources at hands.
The Case for Mars: The Plan to Settle the Red Planet and Why We Must (1997)
Entering Space: Creating a Spacefaring Civilization (2000)
How to Live on Mars: A Trusty Guidebook to Surviving and Thriving on the Red Planet (2008)
I recommended the case for mars first, since it's basically telling the story when the economy in 90's are still able to afford massive 4,500 billions projects travailing to Mars, but he envision a plan that only takes 200 billions. (10 missions each 20 billions, which is very cheap). And by his idea, it's easier to colonized not near earth space, or the moon, but the mars. It's as easy going to the Moon as going to Mars.[1]
[1] Once you overcome the escape velocity of Earth gravity, there is no extra fuel required. There is nearly no resistance in space. All you need is time. And 6 month trip isn't that long, and the packages for a crew of 6 is small enough that you can pack all the food and water to Mars with no problem. And once you get there, you can produce extra water, and even fuels to get back if necessary. In the long run, even growing crops on Mars. Mars soil and conditions are quite suitable for agriculture. (Plants need CO2 not O2, which is abundant in Mars, but not on the Moon)