When a French (or non-native) person speaks English publicly, the most common mistakes are:
Talking too fast
Because you think it sounds cool and more native.
It doesn’t. It just makes it hard for people to follow you.
Skipping sounds
Like saying “worl” instead of “world”, making your speech difficult to understand. After a short while people will lose interest or concentration, and discreetly dive into their smartphones.
Misplacing the stress
Like saying “determine” , “archive”, “hierarchy”, “development”, “ownership” etc..wrongly
Now that’s very important. See “Tools” section
Confusing two different sounds
Like pronouncing “slip” , “hit”, “live” the same way as “sleep”, “heat”, “leave”.
Focusing too much on the spelling
of words rather than concentrating on their sound
