A good, low profile, high lift hydraulic jack and jack stands.
I LOVE being able to both slide my jack under the car effortlessly AND being able to jack up either the left or the right side completely and get stands under it with the jack on the frame rail without having to move the jack.
Ratcheting box wrenches are also a godsend.
97 Thunderbird LX (The GT Bird)
PI Swapped NPI motor with some port work on the heads, PI cams, 80mm MAF, CAI that feeds from fenderwell. Jmod, 3.73:1 TL in Mark VIII carrier, Mark VIII aluminum LCAs, 93 Mark VIII driveshaft, PBR brakes (soon to be Cobras), 18x9 wheels, 255/40/ZR18 Tires, Front and Rear strut/shock bracing, GR-2 shocks, Eibach 1.5" springs, 1989 SC front and rear sway bars.