How did the French and Indian War prepare the colonists for the American Revolution?
England billed the American colonists for that war, which was a big step towards the Revolution.
England prevailed in the Seven Years' War (and its American theater of conflict, the French and Indian War; they were actually the same war) by borrowing heavily and outspending the French. They reasoned that the American colonists should certainly kick in for their own continued protection.
Most English colonists in the New World were there to make some money, which they were unable to do back in the Mother Country. Sure, there were some Quaker and Puritan religious separatists who sailed over for sweet religious liberty, but they were a minority even in their enclaves of Massachusetts and Pennsylvania. Most colonists came over as an investment, and as long as the Crown kept nickel-and-diming them (or, in this case, shillings and pennies), they were not going to get very far ahead financially.
Plus, the colonists had no elected representation in Parliament, This was a sticking point, albeit less of one than the money thing. Their complaints were met with more taxes and a clampdown on locally-elected officials. This culminated in the Boston Massacre, at which point a revolution was inevitable.