As an employer I can tell you step #1 would be to make sure you're worth it to your boss. If you don't know that your boss would be very unhappy to see you go, he probably wouldn't.
Assuming you're one of the most valuable employees, and you have a good reason (ie. your boss is paying you well under market rate for someone of your skill set) then keep in mind that your boss probably won't be upset. Nobody is happy to pay more for the same thing, but they'd be less unhappy than losing you. What an employer pays his employees is often based on what they asked for rather than what they deserved.
Assuming you're one of the most valuable employees, and you have a good reason (ie. your boss is paying you well under market rate for someone of your skill set) then keep in mind that your boss probably won't be upset. Nobody is happy to pay more for the same thing, but they'd be less unhappy than losing you. What an employer pays his employees is often based on what they asked for rather than what they deserved.