By some kind of coincidence :) I was doing a short public presentation few days ago & just few days after that I was in a crowd of spectators during few hours long (yikes!) presentation stream. I hope you'll all agree with me - there won't be any better opportunity to kindle the fire of hatred: let's criticize others! On more serious note: doing presentations on my own is a great way to keep myself humble (at least in that area) - I realize how many things I have to improve & how much effort is needed to do that. On the other hand I see other people who're making the same mistakes again & again - but in the end they always seem to be very happy with themselves... Let's prove them wrong! By listing down the big NOes people still do (but they shouldn't!) in their public presentations:
Not wearing your audience boots
Most likely the worst mistake you can make - it can happen when the presenter ...:
- ... focuses on what's the most interesting for himself, not for his audience (please keep in mind that audience members may be far less proficient with the topic)
- ... dives too deeply in the details and loses his audience's attention because they get lost
- ... doesn't bother himself with giving a proper intro to make sure that everyone in the audience is able to follow the presentation
Having people lost before you've even started
Even the most interesting presentation will fail if you don't set a sensible context first - your audience has to "place the presented objects" properly, to understand the reason why you're presenting that and what are the key outcomes they are supposed to focus on.
Speaking 'towards' set sub-group / individual
My favourite one - pisses my off like ten hells :) The presenter is in front of 30 people, but it's far more than clear that he's adressing a single person - his boss, his main stakeholder, whatever. I DO realize that every presentation has its purpose and its key target audience, but I can't help it - for me it's a clear indication of disrespect for the rest of the audience.
Proving topic's complexity by unreadable bullshit
Another source of annoyance - the presenter wants to prove how significant, complex & critical the topics is, but (s)he does that not using substantive arguments, but by displaying some useless & unreadable bullshit: unclear diagrams, humongous Gantt charts, formidable tables... Irritating, pointless, unclear & ... just lame.
Making an impression that even you're bored
If there's no passion in the presenter & he seems bored with the stuff he's presenting on his own - how does he expect anyone else to get excited about the topic? Isn't it obvious - if you want to prove that something is awesome, you have to believe it yourself first (and appear as such as well!).
Bullshitting, straight in the eye
Credibility dies first & it's really not hard to kill it. First apparent bullshit does the stuff, so just don't oversell, especially when you realize on your own that the thing you're presenting is not even half as awesome as you're pretending it is. Manual testing of 10k slave-made test cases is not awesome nor innovative. Migrating 500 RDBMS data tables is not awesome nor innovative. Period.
Overloading the slides with "the information"
The slides are supposed to be THE AID. To help with structuring the presentation, to provide some illustrative images, to aid navigating through content. And they have to be clear & concise so every audience member is able to skim through the slide content (& understand it!) in a blink of an eye. Slides are not supposed to be horizontally oriented Word document pages - keep it in mind. And if you have more than 20 slides, you're doing something terribly wrong ...
Reading from slides
Continuing what I've just said about the previous point - slides are your map / your focal points, they are not to be read aloud - leave it to your audience, just proceed with the actual content: provide examples, clarify the reasoning, question the thesis, etc.
Good picture is worth thousand words
That's the key - it has to be a good picture. Not a generic image template from a corporate database, but some actual illustration for what you're talking about. The actual technique is not relevant: sometimes I just make a drawing on a scrap of paper (yes, by hand) & put such a picture (taken with the mobile phone) directly in the slides.
I realize that the majority of the comments from the list above is more than obvious, but I can't help that - even people who make presentations every week or so do these mistakes again & again. So it's either me not getting the clue of presentation idea or they just don't care / want / know how to do better ...