Building New Bases:
Scouting:
Once you get Warp Drive you may be tempted to build an outpost ship right away, that is fine. Now just where are you going to send that outpost ship? What, you don't know? Thats where scouts come in. Scouts, with their superior speed, enable you to find a suitable planet to send your outpost ship to. The most effective way to scout is to move your scout to a corner of a neighboring region, just over the edge. You do this so that you have the shortest possible travel time between the four regions and you can hop from across the corner and see all 4 regions in short order. Check every system for good planets (see below for what defines a good planet), bookmarking and labeling the ones you find before moving on. You move a ship by first going to the destination region (from the Fleets screen by clicking on a region adjacent to yours), then picking the system and planet (It has to be an asteroid or a planet, no gas giants or asteroid belts),you want to land on (remember, a corner). Copy the address, then go back to your home planet and click on the fleet there. Select one scout by putting 1 in the box next to scouts. Put the copied address up top, then click move. Now you just have to wait.
Deciding on a Base:
So now you have your scout on its way, or maybe you are doing it the slow way and having your outpost ship search for a suitable planet, but either way, you need to know what to look for.
General:
The most important parts of choosing a new planet center around Fertility, Metal, Energy, Area and Moons vs. Planets vs. Asteroids.
* Metal is very important to choosing a planet as it decides how quickly you can build and also how high your economy can go. Never take a 1 metal planet, and 3 metal planets are superior to 2 metal planets. You should plan on building only on 3 metal planets except in rare cases.
* Energy is an important resource for you to consider, and getting a planet with 3 or 4 solar or gas will make energy much cheaper both in the short run and in the long run. High energy is most important for Production planets, but also is important for Jump Gate planets and planets you intend to defend extra well. Energy should not be chosen over metal.
* Fertility is important as it affects your population capacity. Low fertility can be harmful early in the game, but you can fix it later with Biosphere Modifications later so it becomes less important. Lots of times fertility comes at the expense of energy, and the two are more or less equal in importance.
* Area is something to think about mostly for Production and Research bases. Asteroids have low area and are not very good as either. Planets of course have the highest area, but there are drawbacks to planets. Overall, area is less important than the above 3 characteristics.
* Moons vs. Planets vs. Asteroids comes down to the prices of some structures which are 50% off on Moons and 75% off on Asteroids. These structures are Biosphere Modifications, P-Rings and P-Shields. If you have low fertility, having cheap bio-sphere modifications can be important, so moons and asteroids give some benefit there. If you plan on defending your base extremely well, cheap P-Rings and P-Shields are very important, making moons and asteroids much better than planets. At 10 P-Rings, Planets are better for their increased area, but at 15 P-Rings, Moons become better for discounts on Rings. It comes down to how much defense you want. All in all, choosing a moon vs a planet is the least important choice in colonizing.
* One other important thing is that you don't want your bases too close.
* It is a very bad idea to have more than one base in the same system, and a bad idea to have multiple bases even the same region.
* Having your bases distanced from one another gives you better scanners and scouting in the galaxy, and makes it harder for one large fleet to conquer you.
* So do not build two planets in the same system, and unless you cannot help it, do not build two bases in the same region.