To improve the energy density and address the safety concerns of current lithium-ion batteries, garnet-based solid-state lithium metal batteries (GSSLBs) have drawn attention as candidates for next-generation electrochemical energy storage devices. Battery resistance, energy density and cycling capability are three fundamental indicators of GSSLBs and greatly influence their real applications. The progress toward developing low resistance, high energy density and improved cycling capability is reviewed in this paper based on an aim-oriented thinking. The fundamental effects of improving the ionic conductivity of garnet solid-state electrolytes (GSSEs) and engineering cathode/anode interfaces are first discussed. The significance of thinning GSSEs, decreasing the lithium metal anode level and exploiting high-energy cathodes for energy density is highlighted with the help of energy density estimation models. The benefits of and inspiration from constructing a three-dimensional (3D) configuration anode interface, applying external stack pressure and extending the operating temperature range to further improve the cycling capability of GSSLBs are also summarized. Moreover, the remaining challenges and future perspectives are presented with the expectation that our insights into the fundamentals and regular patterns can provide good guidance for developing better GSSLBs.