1) Find out what crabs like to eat. Probably gross stuff.
2) Acquire lots of crab food and feed a lot of crabs
3) Befriend the crabs. Tell them your vision for a new government. Really sell them on it.
4) March on the seats of power with a motivated crab army of friends and true believers
5) Chase out the scum with your seething wave of claws! (Once you’ve chased out the scum with yr claws, continue to step 6)
6) Set a date for free elections (and ban crab feasts)!