A combination of 2 or more switches - like a combination lock, is definitely better than one - but should be thought of as a SECONDARY line of defence. Make the car appear dangerous to tamper with (alarm etc) and most joy-riders will give it a wide berth. Then make it appear difficult to steal. A "club" or "denver boot" does a good job here.The blinkenlights help too.
THEN make it difficult to start - by whatever means you can devise. Many of the remote starter/keyless entry units have an auxilliary output - sometimes labelled for the trunk release- that can be used as one element of the starter dissabler (press the trunk release when turning the key to start position).
Some also have a starter disable relay that opens the starter circuit when the doors have not been unlocked with the remote. Picking the lock doesn't get them anywhere.
Anything "Donald Duck's cousins" come up with will be "mickey mouse".