Duct Tape - You can use this stuff for an amazing number of things. My muffler fell off on a trip and I taped the exhaust pipe to the bumper to keep it from dragging on the ground. A Bike Pump - You can pump up your tires with this. It is more work than at the gas station, but tire pressure is only measured correctly when the tires are cool - before you drive it. Motor Oil - at least a quart.
Most cars are a nightmare to get transmission fluid into.
A good funnel and a rag will make the job much easier. You have to check the fluid level when the car is running and is warmed up. This information is sometimes found on the dip stick - otherwise check your owners manual. Check your air cleaner element - Hold your air cleaner up to the sun and try to look through it. If you can't see daylight - it's time for a new one.