Primary requirement: Only spend on activities for which the government actor has a comparative advantage (i.e. can do it better, at a lower opportunity cost, than any market actor could).
First example: Various "security" and "war" services: Marines, Army, Navy, Air Force combat personnel. Coast Guard search and rescue. The uniformed beat cop. Fire departments. Criminal court. Border control to prevent entry of criminals and infectious diseases.
Does not include such things such as REMF functions, police detectives, or anyone or any function provided bye the so-called "Department of Homeland Security". Does not include enforcers of "limit immigration" laws.
Second example: Licensing of renewable resources where without some mechanism to exclude users, the renewable resource would be used up. Fishing and hunting licenses, for example. Park rangers and the collection of fees for use of public parks, wilderness preserves, and the like.
Third example: (Some) roads, bridges, navigable waterways, coastlines, and the like. Not all, however -- if it is possible to prevent free-riders (e.g. by tolls), then there is no need for the government to be involved. City streets -- yes. Interstate tollways, no.
Secondary requirement: Only if the government and those who work for it are willing to accept civil liability for breach of contract and for intentional and negligent torts they commit. No sovereign immunity except in cases of bona fide emergency national defense in response to outside aggression by other states. And absolutely no immunity to be extended to elected officials, non-combat personnel, general officer in any service, or any civilian employee with a title of "Assistant Secretary of ..." or above, that is not also extendable to non-government individuals.
And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God.
Romans 12:2 (NKJV)