Star Photography?(yosemite)?

Hi i'll be in yosemite national park in a few days, and i wanted to take some night pictures/ landscape pictures

doyou have any tips for me?
and more specificaly what should I do to take nice star pictures?
I use a nikon d80, but i won't have a tripod

That's fine. You can do this without a tripod. Just rest the camera on a convenient rock or something and use the infrared remote. If you don't have one of these, get one. They are only about $25 and worth their weight in gold. Put the camera on manual (M), take a few shots at different settings to get the lighting right and go for it. Also, it helps to have some sort of ground based reference point in the shot: a clifftop, a mountain, a tree or something. Have fun.

If you can find a good used MC-30 remote, you can take some many hour long shots which will give you some great start trail shots.

EDIT: Oops! your camera will not take the MC-30. You will have to use the MC-DC1 Remote Control

You just have to set your camera on "B" (bulb) and then lock the remote down for as long as you want. You can set the camera on its back, on the ground and there you have it.

Landscape shots will require a nice wide angle lens. If you have a 12-24mm you are golden, if not then you may have a 18-55mm. In any case use the widest angle lens you have to shoot the landscapes. Those can be shot handheld