Below are a few of them. Don't let these rules scare you off from building a device.
Many projects work fine the first time.
It's when they do not work that the following suggestions start becoming useful. Some types of static electric generators can only supply an extremely tiny current. The lower their current-generating capability, the more sensitive they are to stray leakage paths. But if you try to use a Kelvin Waterdropper as a power supply, you'll probably have to follow all these rules in order prevent surface leakage from shorting out your system. Also, if you follow all these rules, your device may tolerate much higher levels of humidity than otherwise.