You absolutely must consult a factory service manual for your specific vehicle year and engine. This manual will provide the correct sequence and torque specifications for each stage of the tightening process. Using incorrect torque values can lead to head gasket failure, warped heads, and significant engine damage.
These manuals can often be found online (through reputable sources, be wary of scams) or purchased from automotive parts stores or online retailers. Investing in a factory service manual is highly recommended for anyone working on their own vehicle.