1. Housekeeping tips should be placed in an obvious location like the dresser or the bed. Because you may have a different housekeeper each day, several advisors suggested tipping daily, "which also might get you better service." "Don't leave castaway items in place of a monetary tip," stressed another advisor.
   The average suggested tip amount is $2-3 per day and up to $5 per day if you're staying at a 4 or 5-star hotel.
   
2. It's fair to take into consideration how much mess you leave for housekeeping to deal with. Did your kids spill something on the couch or make a mess that will take extra time to clean up? That deserves combat pay.
   
3. The tip also should vary depending on how many people are in your room or suite. If you have three or more travelers staying together, increase the tip by $1 per additional person.
   
4. Valet tipping averages between $3-5 and is presented after the valet retrieves your vehicle. This is customary for any hotel valet, even if parking is included. No tip is expected when you drop your vehicle off.
   
5. Bellmen should be tipped $1-$2 per bag. You can also tip $5 flat plus an additional $1 per bag if you're traveling with a large group. If your bellman provided an excellent orientation, you might consider tipping a few dollars more.
   
6. If you're staying somewhere that provides a high level of butler service, $25-$75 per day is customary. It can be more or less, depending on the level of luxury in your accommodations and on the services they provide for you. We recommend providing the butler's tip at the end of your stay in a sealed envelope. A personal note is always appreciated as well.
   
7. Shuttle drivers should be tipped; $5 per person is customary for short trips to and from the airport. Plan to tip more for longer trips. If you have bags, it's customary to tip an additional $1 per bag.
   
8. Concierges do not expect to be tipped for giving you directions or making a dinner reservation, but if your request is a bit more complicated and time-consuming, consider tipping $5 or more per request. If the concierge pulls off something amazing, like getting tickets to a sold-out show, then your tip can range anywhere from $35 to $100.
   
9. If the doorman is just holding the door, a thank you is all you need.
10. However, if the doorman is hailing a cab, we recommend $1 or $2 and if they are helping with bags, $1-$2 per bag is standard.
    
11. Untangling a gnarly room situation is not tip-worthy, travel advisors say. "That's expected from anyone working the front desk in hospitality," said one. If they re-configure you to be closer to your family or you get an unexpected upgrade, consider tipping with a nice online review.
    
12. Room service bills usually include a service charge, which you'll see on the bill. If there is no service charge, 15% 0 20% is customary.
    

Note that customs vary greatly from country to country. In fact, in some countries, tipping is considered an insult, so ask your travel advisor or investigate local customs when you're traveling abroad.