The design of electronic switched-mode power systems has become increasingly complex due to the introduction of gallium nitride (GaN). GaN's electrical properties, including the absence of a physical body diode and lateral device operation, allow for new power topologies like hard-switched half-bridges or bidirectional switches. System designers must choose the best concept for their needs, and there are no cookbooks or simple algorithms for this task. This whitepaper provides guidelines, rules, and trade-offs for designing a power system using high-voltage GaN switches, referencing additional technical documents for further details.