Sentences to start a presentation

"Ich möchte ..." means "I want ..". But nobody is interested in your desires when you start a presentation. People want you to present something. So, better beginnings are:

Heute spreche ich über ...
Ich erzähle Ihnen heute etwas über ...

But the audience already knows that you are here to talk to them. So, there is no need to tell them that you talk to them. They are clever enough to realize this very conspicuous fact.

I think the best beginning is a question. There are closed questions that need to be answered with yes or no:

Did you know, that ...?

But much more interesting are open questions: questions that start with "What" or "How" or similar question-words:

What will happen, if ...?
How does a ... work?

But even better: include the audience! Ask them what they think:

What do you think will happen, if ...?
How do you think does a ... work?

And you can ask the very same questions in any language, also in German:

Was glauben Sie passiert, wenn ...?
Wie vermuten Sie, dass ein ... funktioniert?

The audience will be curious about the correct answer to your question. This creates tension, and the audience will listen to you much more interested than if you told them that you want to do something.

At some point in your presentation you will have to give a clear and understandable answer to your question. The best moment is at the end of your presentation. And everything between the initial question and the answer must be a story that leads from one step to the next. Never forget that your presentation is only good if you tell a fascinating and pulsating story. It begins with an interesting question and ends in an surprising answer.