Tipping very much depends on whereabouts in the world you are travelling. If you’re heading to America, tipping is a big part of the culture and is expected when paying your dinner bill, buying drinks at a bar, and even getting a taxi. However, if you were heading to Japan, tipping would be seen as impolite. In most parts of Europe, leaving a tip of around 5 - 10% of the total bill is the standard, although make sure you check the bill first, as a tip may have already been included in the total cost of the bill. It’s generally worth reading up on the tipping culture of the region you are travelling to prior to your trip, or just ask your Trip Manager what the general etiquette is once on trip.
In terms of tipping Contiki staff and Local Guides, this is entirely up to you and is not compulsory. If you think a Trip Manager, Driver or Local Guide has done an awesome job, you may wish to tip them for this, but this is at your discretion and no one else’s. Tip what you think is right only.