If you're new to smart homes, it's tempting to buy a bit of everything at once. A more useful approach is to start with the upgrades that change your daily routine the most, then build outward from there.
Smart lighting is usually the best starting point — it's the cheapest single upgrade, it's visible every single day, and scenes and schedules make an immediate difference without any behaviour change required from anyone in the house.
A video doorbell or entry camera is a close second: it answers the single most common "who's at the door" question without you having to get up, and it gives you a record of who came and went.
Smart plugs are the quiet workhorse of a smart home. Any appliance that gets left on by accident — a heater, a curtain motor, a coffee maker — becomes schedulable and remotely controllable the moment it's plugged into one.
A smart lock is worth adding once you're comfortable with the rest of the system — it replaces physical keys with app or PIN access and makes guest access far simpler to manage.
Finally, tie it together with a couple of automations — an "Away" scene that locks up and turns things off, and a "Good Morning" scene that starts your day — so the system starts working for you instead of the other way around.
The real energy savings from automated lighting.
SecurityCCTV, locks and sensors — what you actually need.
AutomationOne-tap moods versus rules that run themselves — when to use each.