Your starting point is to determine which reloading data source are you going to use. Nosler, Hornady, Hodgdon, even Barnes offer data. You cannot load without this data.
I am a big Nosler fan because I find them to be the best. Their books used to contain details on loading but that seems to have ceased. Check used book store you may find older manuals.
Next determine which caliber you want to start with. Begin to read everything you can find.
I create a reload folder on my browser and every article, component source, link, you name it goes in that folder.
You will need roughly, estimate here, $500.00 in reload components. Press. Dies. scale. case prep tools. Primer seating tools. micrometer. a peaceful quiet place where young kids and flames along with breezes are not present. Later on you will need brass cleaning equipment.
Buy once cry once is very true when acquiring reloading hardware. I have 4 primer seating tools and only use 1-which is more expensive than other 3 combined and strangely enough well worth the cost.
Never ever guess.
Always check your scale zero before you start weighing gunpowder.
Always create dummy examples of what you think is the correct size (no primer or powder) and insure they will cycle through your rifle.
Examine your first round fired for overpressure signs. Flattened primers are first, sticky bolt lift is next. And yes, get a rubber mallet.
Keep written records of your work.