Accent in English speaking: German speakers are a lucky few, because even if they have the typical, horrible accent when speaking English, it’s one of those which everyone can still understand. However the Germans also have something called "Denglisch", a bad mixture of German and English words, which can lead to misunderstanding. For instance, the German word "Handy" means "mobile phone", and if you mix that into an English sentence, people will be justifiably confused since in English, "handy" means "practical" or "useful". You should be aware of your own accent and such language traps and avoid them. Clearly, speaking perfect English is harder for people of certain cultures, but everyone should try their best when talking to an international audience.

The typical stereotypes and prejudices about how certain peoples speak English very often hold true, especially if speakers are unaware of how they speak English, so you may be able to just find out something about your culture/language/people by researching (insulting) comments about it. Seriously! To give you a personal example: I googled "german speakers accent horrible" and found e.g. Why are Germans among the worst speakers of English?, which felt somehow insulting, but since as an adult I don’t care much, I read on and found quite good reasoning by the author and others.

The difference of languages and cultures is a big source of trouble in listening comprehension and a topic of its own. I might give more hints on that in a future article, but here it is too much.

Summary: be aware of how you speak! If you know of your accent, and hear that you cannot avoid it completely, at least try to speak slowly.

Do not turn around to your slides on the wall: you should have a mirrored display (or presentation mode) on your laptop or second screen. You are turning around because you are feeling unsafe — similar to putting a hand in your pocket. Knowing your content or at least the order of chapters helps not needing to look up the slide content all the time. Presentation or mirror mode can show you the current and/or next slide if you need to see it.

Practice: Many people don’t like rehearsing their presentation in front of a mirror, with family, colleagues or friends or even by themselves. That’s natural and often even unnecessary. Regarding stress level: you are not in a job interview (if you are by any chance, ignore this hint), no need to haste or feel unsafe. Think less and keep the presentation style simple and your voice calm but controlled. The slower and more calm you are, the lower the risk for increased stress levels are. Watch a few minutes of Louis Dionne’s Meeting C++ 2016 keynote to see the meaning of that hint. He is the best example — exaggeratedly calm in some people’s opinion, but yet doing a perfect presentation with close to zero glitches or mistakes 👍.

To get a real preparation for a bigger event, you can try a local meetup group, present at your company or in another small setting. You could extract a small part of your slides into a lightning talk to check if people like the topic at all. Request and collect feedback from the rehearsal/practice session audience.

Speak loud and clear: Some rooms simply have bad acoustics and you can make up for it with your voice. It also makes listeners think that you are feeling confident about your topic. But do not speak too fast — as mentioned above, try to keep your pace and style calm.

Know your own quirks: You should be aware of your own behavior and speaking. Practice and feedback can help find out what you didn’t know yourself yet or didn’t want to realize. Example: many people say the same words or phrases all the time. It’s a pity that humanity is so fearful that we do not tell each other, but no way to change that at large. I know there are people who have that as invalidity or uncurable illness, but for the ones who can control themselves — just listen to yourself to find such tics. It even happens to keynote speakers ("you know"). Other popular words to accidentally repeat are "I", "so", "amazing" (or similar), "like" and of course "ummmm".