It’s a question that confounds even the most seasoned travelers: Just how much are you supposed to tip the staff during your hotel stay? And, what about tour guides and drivers? Also, the attendant looking after you on your cruise?

Josh Alexander, a travel specialist at the New York City-based Protravel International, has written tipping guidelines for his clients.

“In my experience, no matter how much they’ve traveled, people tend to get confused and even stressed when it comes to tipping,” Alexander said.

Here, he shares advice for travelers:

At Hotels, Tip Directly: Many travelers will leave a cash tip in an envelope at the front desk at the end of their stay and ask that it be divided among various departments, but Alexander advises otherwise.

“You have no guarantee that the money is going to get to the people it should,” he said.

Instead, tip the employees directly who have served you throughout your stay. Whether it’s domestically or abroad, at a luxury hotel that number is $5 a day for housekeeping, $3 to $5 per bag for bell people, and $2 to $3 for employees who call you a taxi or hold the door open for you. The tip for the concierge depends on how much you use his or her services. For a simple dinner reservation, $5 to $10 is enough, but for more elaborate requests such as tickets to a sold-out show, upward of $50 is in order.

Use a Worldwide Standard for Guides and Drivers: No matter the country, Alexander said that for a private, English-speaking guide who spends the day showing you the sights, tip $25 to $50.

“Good guides will include atypical stops such as taking you to their personal friend’s art studio and are also willing to go over their scheduled time with you and should be tipped more,” he said.

For a driver, $15 to $25 a day is appropriate, and for half-day tours, guides can expect $15 to $25, and drivers, $10 to $15.

The one exception is a tour that begins very early in the morning such as the 3 a.m. start for the hike up Mount Haleakala in Maui to see the sunrise. In cases like this, add another $20 to $25 on top of the usual tip.

Also, Alexander said that guides for group tours can expect $10 to $15.

Cruises, Safaris and Train Trips Are In a Separate Category: On trips such as these, Alexander said that a small, dedicated staff or even a single employee is likely attending to you throughout your stay.

“On a safari, your ranger is taking you on game drives and also looking out for your needs at the lodge. And on high-end cruises and train trips, one person is usually overseeing every aspect of your trip such as helping you unpack and pack,” he said.

These people should be given $20 a day. The exception is if a tip is included as part of the trip price.

“In this case, there is no expectation to tip extra, but you can if you feel like you got knockout service,” he said.