Need a little more data, your experience, type of rifle you will be shooting and what you consider long range.
Before you gear up, you need to have a solid understanding of external ballistics and how it applies to long range shooting. Given that, you will then know what you need.
Ballistic software or slide rule (FDAC)
Data book can be a simple memo book, something to jot down the environmentals, your calculated dope, vs actual dope.
Then tools to record your enviromenatals, Kestral or similar to record wind speed, temp, pressure and to calculate density altitude.
Something to shoot at, steel gong or some type of target
Lastly a crap load of ammo.