First, try to get materials, most importantly metal, from the storages near the main dome. And a set of tools, you'll need a crowbar.
Then head straight south till you hit the end of the map and then keep going west as fast as you can until you hit the western end of the map.´
Start building a fortress for yourself. No one ever goes to the most south western corner so you're pretty save for now. Start with setting up alot of girders or wooden barricades blocking the way. There should be two entrances, north and east which you have to block off. Make sure to make some of the girders into fake walls so you can get out and in.
Now that you have set up basic defenses, make sure to decorate your new home. Maybe hang up some posters? Just watch out for that skull-hungry predator.
Once you've set up your new home you can go ahead and wander off to new horizons, looting and plundering wherever you see some nice booty. Just don't let yourself get seen by those pesky xenos. I suggest going to Tcomms and Engineering and getting yourself a hardsuit and fire-axe for combat.
Optional:
Break into the armoury at the main dome and take 2 C4, maybe some meds, EMP for the pred incase he hunts you and the guns at the firing range. Now head to the vault dome. There you can loot the mech (for better equipment for the mech you'll have to head to the robotics dome) + infinite power cell (It's in the safe in the vault dome), a flamethrower + tank and the nuke disk. (For either blowing everything up incase you manage to steal the nuke too and get a code from the admins or to trade it in against some valuables)
Now it's time to go back to your home and wait a good time until the marines arrive. From now on it's going to be easier.
Once the marines arrive go to the pod and steal the equipment from a SSD marine. If there's no SSD marine wait a bit in your home until the first people die and then go scavanging the dead corpses lining up at the LZ.
Now you're pretty set-up. You have a fortress which you can live in and defend your precious loot and you have a basic set of marine equipment which you can use to defend your base with.
Optional:
If you can, head way up north past the river and get some sandstone from the pod-like materials storage, better bring your tools to destroy those walls. The sandstone allows you to build hydro pods out of earth, which allows you to make food in return. Better head to hydro, to get your basic supply of seeds and gardening tools.
![Wink ;)](images/smilies/winking.png)
From now on you can pretty much go out and keep looting, do what you want or go mad, while talking to your imaginary best friend in your base.
I've only tried this once so far and it worked succesfully. I've only encountered a alien once when I was in my base, but it only spit acid at the girders and never came back. No one botheres with the south west.
![Image](http://oi57.tinypic.com/29kzzvn.jpg)