If you have something exciting to say in a presentation, don’t follow it up immediately with “but”, it flips the emphasis from the good news to the bad. Don’t use “buts” in your content.
For example, don’t say “The new program offers real opportunities, but the ordering system is more complicated.”
A better way is to separate the two thoughts and drop the but. “The new program offers real opportunities, (pause) and a few challenges with the ordering system.” In this way you don’t yank the rug out from the good news.
Avoiding “buts” also allows you to appear more positive, body language-wise.