New house... What would you do as you move in.

[M3 Mitch]

While the house is empty would be the time to paint the walls, and/or replace carpet/refinish floors. Concentrate on things like these that would be a PITA once you have moved in.

If you can swing it, staying put in your current digs for say a week while you at least give the house a good cleaning would make that job easier.

[Dytecture]

First day I would measure up the house and doing a furniture plan for the entire house. I would also think about colors and the decorations.

For other DIY or home improvement projects, I would live in the house for couple months, see what's working and what's not, and decide which project to tackle based on my budget.

[Charles]

One of the first things I did here in southern california is have an earthquake gas shutoff valve installed.
Other things: CO detectors, Fire extinguishers, emergency lighting if the power goes off (little LED things that plug into the outlet), security lighting on a motion sensor outside.

Another thing I did was run street pressure (135 psi) water to the backyard because the backyard bibs are house pressure (55psi). I tapped into a pipe upstream of the pressure regulator and ran PVC to the backyard. This way I can have a super powerful hose for cleaning up.

WD-40 the faucets and water control knobs.

Plant deciduous trees on the east and west sides of the house.