There is no rules to follow on any design - just a methodology which suits you most.
Typically, analog design would start from schematic, downto simulation, verifying that the circuit that you created is functionally correct. Then, prototyping on a breadboard with all the components available and testing it out using oscilloscope or multimeter.
Today, EDA tools have advanced in such a way that there's tool for everyone. Schematics/simulation tools like Hspice (Synopsys/Avanti), T-Spice (tanner), Tina Plus or other Spice simulator. If you are looking at large design system, a more powerful tool like Saber (synopsys) might be helpful.