Tips for shooting large photos with Nikon D3000?

I have a Nikon D300 and I want to take a few photos of my friends to frame and put up on the wall. The size would probably be 24"x36". I wouldn't want for the images to be pixelated for trying to print them so big.

Whether you have a D300 or D3000, shoot in RAW and then after processing the RAW images, export (or save them) as TIFF files. These are uncompressed files and will show none of the artifacts associated with large prints made from JPEG files

The tips I'm going to relate apply to all digital cameras!
1. Set the camera for maximum resolution. This is the single most important thing you can do!
What does maximum resolution mean? Go into your menu and the section that gives the choice of the amount of pixels the camera records at. Choose the highest figure! This is also expressed as the LEAST number of pictures available for the memory card installed in the camera at the time of this setting. EXAMPLE: So if setting #1 = 80 pictures; setting #2=40 pictures; and setting #3=20 pictures
YOU choose the setting that yields the LEAST number of pictures available.
2. Choose a small ISO. The = the sensitivity of the camera's sensor. The smaller ISO the better the image quality. So if your subject (s) are sitting for you, you can use a low ISO i.e. 100 or even lower ISO 50.
3. Camera MUST be mounted on a tripod.
4. Your lighting should be even. (a studio setting with the light bounced into an umbrella is flattering).

You will certainly need good lighting, Low ISO and aperture set at either two stops below max or f/8 for best sharpness. A 24x36 can be difficult. You need a really high quality shot or any flaws will start to show up.