Some ideas that apply to all areas of work, as you didn't specify
- A Ratchet/Socket Set, I recommend C.K, Wera, Bahco, Draper, Wiha (For a VDE set) and Stanley.
- Set of screwdrivers, I'd personally buy, C.K, Wiha, Wera, Knipex, Bahco, Draper, Stanley or OX.
- An organiser for screws, crimps...