One of the fun things about building electric guitars is wiring them up. Factory wiring tends to be simple, minimizing the amount of fussy handwork required. Many manufacturers keep strictly to 'classic' designs, seldom if ever changing anything. These designs are generally simplistic, often crude or even stupid, and sometimes outright flawed. There is no need for you to do this. I don't. Here are some of the things I have done over the years. I don't claim to have invented any of this, although some of these schematics I have never seen anywhere else, and had to derive them myself.
The commonest form of pickup combination is parallel wiring. This is absolutely simple - a two-pole switch [OFF-BOTH-OFF] disconnects either of the pickups from the output. The [OFF-BOTH-OFF] switch is actually kind of a rare thing. You won't find one at the hardware store.
Parallel wiring is easily extended to more pickups, although three is usually the limit.