There's two type's of security. Preventing it being stolen or at least making it more difficult. Out of sight, alarms, immobilisers, steering locks and pedal guards etc.
The second is identifying and locating it after its been stolen. Etched windows, trackers, paint etched, reg number painted on the roof etc. The first thing robbers/theives do is change the reg plates to stop traffic monitoring camera's from knowing where its going. Often with plates from a similar vehicle. Especially if left on the side of the road to see if someone finds it with a tracker.
A tracker that tells you its moving is much betterer than a tracker that just reports location when asked. Yer need to know when the theft is happening to give yer time to react. Automatrics will go out on the road and find it and report to the police for recovery. Tracker uk have monitoring kit in some police cars which picks up the signal of distressed trackers. Skytag have a lesser service where they only follow it from the office but do report it to the police after you confirm its been nicked. Their claim on battery life it bollox. DefenderDefender reports movement but you track it yerself with their system.
If you have keyless entry locking/unlocking on a D3/4 or range rover then disable it. You may consider it as a vital feature so yer don't need to search yer hand bag for the key, but robbers/theives use this feature to help them unlock and start these vehicles anorl. Yer can disable it without tools yerself.
https://www.landyzone.co.uk/land-rover/turning-off-keyless-entry.325670/