Effective hourly rate = base hourly rate * risk. Risk = client risk * task risk. Client risk is based on your past experience with the same client. If they're

Effective hourly rate = base hourly rate * risk. Risk = client risk * task risk. Client risk is based on your past experience with the same client. If they're prone to demand last-minute changes or stupid stuff, they get charged a higher rate on every project afterward. Jacking up the client risk factor is also a nice way to fire a client you don't want.