Buy:
Tumbler to clean brass
Scale with check weights
case gauge
Calipers to measure various lengths
Bullet Puller to fix mistakes
Primer flip cup
RELOADING MANUAL(s) Lyman 49th is good
A light you can angle down into press to make it easier to visually confirm powder charge
A chrono is good if you can afford.
For selecting the load, as others have said, go to the powder MFG site, and cross reference with a manual. Start low and load small sample lots. Use the samples to determine things like function and feel and refine from there.
Plunk test to assure you have an OAL that will work in the intended chambers before loading. Make some sample dummy rounds to verify they will cycle.