Leaving the correct amount for a tip often presents a hassle, whether you're at dinner with friends or trying to figure out how much to give the bellhop. Throw in vacation and a country with completely different gratuity rules and the confusion mounts ever further.

Diane Gottsman, owner of The Protocol School of Texas, has assembled a general tipping guide when traveling in the United States. Here are some tips to tip, at home and abroad.

As a general rule, tip anyone who helps you out, whether it be to the car or with the door: valet drivers, concierge, hotel housekeeping staff, poolside attendants and baggage attendants should get gratuity.

At the airport, the skycap gets around a dollar a bag.

"More if the bags are heavy or if he or she has to wait while you rifle through your bags for your photo id," Gottsman says.

But members of airport security and flight attendants do not get a tip-Gottsman calls this move inappropriate. Their job is not one in the service industry, per se, so they go tip-free.

Once you arrive at the hotel, make sure you tip anyone who touches your bags. For instance, the person who removes luggage from the trunk of the car and gives it to the bellhop should receive a dollar or so. As for valet, one usually tips upon departure, but if the valet helps with the bags, do give some gratuity.

Gottsman suggests leaving a daily tip for the housekeeping staff, rather than one tip at the end-housekeepers work by shifts, and chances are, money left in bulk could get lost in shift rotation. Leave some cash in an envelope, or bare, somewhere the staff cannot miss it.

The concierge's tip varies depending upon how helpful she or he is: for making a dinner reservation, no money is necessary. But snagging elusive tickets to a show, or having a huge floral arrangement sent to your hotel deserves a bit of cash. Gottsman suggests between $5 and $20.

It is not necessary to tip hotel maintenance staff, like a plumber or electrician.

At the bar in the lobby, tipping goes as it does in your hometown: $1 per alcoholic drink, per person.

These are the rules that apply to American vacations-overseas, it's a different story. Each country has a variant standard for tips, but broadly speaking, tipping in Europe is rare. The tip is often included in the bill, but some say it bodes well to leave a little something extra-typically around 10 percent.

In some Asian countries, it is customary to go up to the waiter, hairdresser, or bartender and hand them the tip.

Make sure to go get small bills before vacation, and do a bit of research on the tipping policy of your destination.