Hi, Robin. Assuming that you have a concrete driveway, starting off with a good wash and rinse with Tri-Sodium Phosphate (TSP) is the most important thing. TSP is available in the paint department of your home center. Spray some water from your hose on the oil stain and sprinkle on the TSP, let it sit for half an hour, scrub with a stiff bristled push broom (or a wood backed laundry brush if the stain is real small but don't get any of the strong TSP solution on you), then just rinse with the hose.
That should get most of it but if this doesn't work to your satisfaction, then take Jay J's suggestion and take another walk through your home center. Getting an oil stain off fast so the oil doesn't get absorbed into concrete helps the clean-up a lot. The longer it goes, the harder it is to remove.
If you do have an asphalt drive, the asphalt is made of oil and the stain will pretty much disappear on it's own as it ages. Putting sand or "Oil Dry" on puddles and sweeping it off after a day or so will help with fresh stains.