I know this sounds obvious to most folks. The springs go on the screw between pickup and the thing it hangs from, pickguard or bridge base. The screws pull the pickup up, the springs push it down. If the springs are conical, it doesn't matter much but I put them on wide end against the pickguard in the assumption that this stops the pickup rocking as much.
FWIW the screws are long thin round head Phillips (two Ls) wood screws, No.3 if memory serves but longer than normal for this size, probably 35mm but you can cut them with stout pliers if they're too long.
If the neck pickup is body mount then you can use springs or foam rubber (pickup packaging), but you must make sure that the screws do not go through the back of the guitar body, easily done.
Humbuckers usually have a small thin machine screw (nut&bolt), and feet that will want that humbucker rout deepened north and south with a pair of recesses to accommodate them.
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