Buy ramps. If your cars are low to the ground you must buy appropriate extended ramps. Make sure you have a location that will take in your old oil. Auto Zone used to take it. Buy oil filters in bulk. I buy name brands from Rock Auto for my Camrys. I also buy jugs of appropriate oil. Walmarts Super Tech brand is a great oil at a great price. The biggest thing is making sure you can conveniently (and legally) dispose of your drain oil. The jugs the oil comes in are great for your drain oil. Get a drain bin with a nice easy pour spout that fits into the oil jugs opening.