Penetrating oil, I suggest trying a couple of different brands to see what you like to use. I always keep WD40 on hand no matter what other penetrating oil I have, I use it to clean tools before they go back in the box.
Cutting oil, if you have taps and dies make sure you have cutting oil. It will help keep them sharp, and make using them easier. It also helps with drilling thick or hard metals.
Drill Bits, a good set of drills bits is a must, sharp drills save you time and effort. Having a decent selection of sizes can really help
Floor Jack, Don't skimp when it comes to a jack. It doesn't have to be expensive, but gett one with some lifting power and a decent foot print.
Jack Stands, multiple sets, come in handy