So here are a few thing that I try and do when doing star timelapse:
1/ always add some kind of static object in the shot, for example a cork, tree, mountain etc.
2/ try and not have some kind of little roard/path in the frame, it may end up screwing up your timelapse
3/ test a few spots before doing the whole timelapse (boost the iso to the max so you don't have to wait to long on the shutter since it is only to find a cool angle)
4/ Always put the camera in all manual mode, and also for the focus well at least on the Nikon on my sister the best focus point is just slightly before infinity.
5/ once the timelapse is on don't mess with it, I usualy check if the shutter is still going off every 30 or so seconds. But if for some reason you have to go close to the camera I heard that you should use a red light to perturb less the picture.
6/ I always shoot in jpeg and raw
7/ when setting the intervalometer don't forget that the camera has to possesses the image before doing a new one and it sometimes takes time (at least on the dslr of my sister)
That's all I can think of for now.