Tipping culture varies widely across the world. Whilst tipping is unlikely to cause offence, it is not always expected (this seems to be the case in Scandinavian countries, Malta) whereas is some places it very much is, so it is worth doing some research first to ensure that you are aligned with the local culture.
The USA is very much a tip based culture with pretty much a minimum of 15% expected for basic service. You will generally find that, even when paying by card, you will be presented with a screen for tipping and it is a brave soul who will cancel that in front of their server!
In Egypt (and I believe in other Middle Eastern countries, some of Eastern Europe, parts of Asia), the tipping culture is a bit more extreme, with a tip expected for every service interaction. A service interaction is essentially any time someone gives you advice, directions etc. This is referred to as “baksheesh” and is a deeply embedded part of the culture, so be prepared to tip often!
Some other things to consider:
It is always worth making sure that you have some cash, as well as physical cards and your phone. This may be unusual, but on my last day in Egypt, there was a major internet outage and none of the card machines were working. It was impossible to buy anything other than with cash.
Some countries prefer foreign currencies rather than their own, especially if there is an inflation issue. Dollars are generally preferred, followed by Euros, with Sterling being accepted at a pinch. It is worth carrying a stash of small denomination notes for tipping wherever you travel, and ideally some dollars if travelling outside of Europe and the USA.
If you are staying in a hotel for several nights, make sure that you tip housekeeping. Apart from being good form, it usually ensure that you get clean towels etc.