We need to firstly be far more thorough in our techniques, and the elimination of possible contamination be applied under strict controlled conditions. It is difficult or near impossible to do this in most cases, especially when investigating a private home where the people are still inhabiting the home and we may only get one or two visits to access the property. This makes a controlled investigation impossible – it usually comes down to personal experiences, spikes on EM meter and, if we are lucky, a blurry shot of a fleeting shadow on a wall. Sometimes a barely discernible voice on audio. None of this could be considered as real evidence to bring to the scientific community to warrant further investigation.
What may be needed is a site that is not inhabited, and not connected to mains power (that could possibly faulty or just with old wiring). As free from outside electrical or human contamination as possible and able to be closed off for extended periods of time. This would probably be hard to find in New Zealand, but I am sure there would be something in Europe, as they seem to have supposedly haunted sites in abundance there.
The site would then need to be well covered by cameras, sensors and detectors, and viewed remotely so as to have no possible interference from people conducting the experiment.
After this is done 24/7, and perhaps much longer still, you can then introduce the human element to the experiment, and observe if this changes or enhances the paranormal state of the site. All this said, it will take a lot of effort and money to do anything of this nature, but until we become more efficient, thorough and perform more controlled investigations, we may never be seen as more than just as fringe -dwellers of science by the wider scientific community. The ball is in our court. We need to up our game or we may remain on the fringes.