The wiki is your friends, however it is updated to only 0.8 rn so expect some things to be different(farming is less op now). Passcode to most doors is either 1234 or 1111. Turn on some lights; the hallway lights are in the small room connected to the garage. Head to your computer and turn it on. Check your email and do what it asks. If you're in 0.9, get some trash bags (singular is best price, buy a lot) and start bagging the garbage piles. There is a mattress upstairs, but I usually bring it down to the signal room. There should be a sponge around somewhere to clean the walls and windows. Do not upgrade you signal processing level until you get speed upgrades! Aside from that and the tutorial, you're set! Just don't spend too long in the basement.
Edits since I did this very late at night:
- The sponge is inside the shower area
- You can break down large objects with the hacksaw and a crowbar
- make sure to compress trash into scrap
- Shovel trash to make trash which can be turned into scrap which is used for crafting
- The mattress works, but you should get a sleeping bag
- Idk if its broken in 0.9d/e, but 0.9c the incinerator doesn't make fuel