If you've just gotta pick up that brush and bowl, at least make safety a priority. The first (and arguably most important) tip, according to Schaudt: "In my professional opinion, I would avoid any colour that contains ammonia in the developer." Although this is an extremely common ingredient in the hair-dye industry — it's effective, no doubt — using it is ultimately a tradeoff; the powerful chemical damages your hair in the process.
What to Try: Josh Wood Colour Hair Dye (£10)