You want to look for a spaghetti squash that is firm and dry. No cracks in the exterior (scratches and marks are fine). You also don’t want it to have any bruised/soft/mushy spots on the exterior.
Brush the squash with oil and sprinkle with salt and pepper and roast in the oven for 35-40 minutes. Once its cooled a bit, separate the strands gently with a fork and enjoy!