Best piece of advice I ever got is create a detailed agreement before you accept everything. When it starts,when it ends, hours for sleeping, a general itinerary of plans,agreement of any costs to be handled by the client such as meals etc. You should go into this knowing exactly what they want and how everything will go and make sure you both agree with it before anything happens.
Things can change of course clients often have overblown expectations of their own sexual appetite. The ones I did we went out on a date then after a shower some foreplay and sex rested and talked maybe have sex again and then they are dead by that point so maybe another shower and bed lol.