The best method I have found is to think in terms of a 5 paragraph paper --  
Intro -- 3 main points -- Conclusion.  The detail and length of time you can
spend on each depends on the time allotted to your presentation.  Obviously,
a 10 minute presentation will not be able to cover the same detail as an
hour session.

While you are creating your presentation, think in terms of bullet points
(ideas you want to hit) but avoid presenting the material in that format.
Instead, try to think in terms of graphics.  For instance, if your
presentation is on transportation, draw a truck in sections.  The cab might
be the trucking companies, the box the supply warehousing, and the wheels
the timetables for getting stuff where it needs to be.  This is, of course,
very simplistic, but the graphic will mean much more to the presentation
than a list of bullet points ever will.

Know what rules apply to your presentation, company colors, logos and how
they are allowed to be used.  Try to create slides that use pictures and
graphics (and perhaps some very simple animations) that will support what
you are talking about.  The PowerPoint should support and supplement what
you are saying, it should not be thought of as a replacement for the
speaker.

Once you have your talk roughed out, rough out your slides. Rehearse the
talk to your mirror out loud.  It is important for timing and knowing what
words to use that you speak the words out loud and not just mumble to your
monitor. Then find a trail audience and present your talk.  This audience
should be a friend or a coworker or better yet a spouse.  Give the talk to
them (use a timer) and ask them afterwards what worked and what did not.
Take these comments very seriously, write them down and start to edit to
improve.

After you know what you are going to do, it is time to refine your slides.
Find quality graphics, that do not distract from your subject.  Continue to
rehearse your talk using the slides and a tape recorder.  Better yet, set up
your video camera; tape and watch yourself as you are giving the talk.  You
do not want to appear to be reading from a script or to be seen as hiding
behind a lectern.  Check with a trail audience again, what needs to be
improved?

As the speaker, the main focus should stay on you and your slides should
only draw their attention when you want it to (when it helps with one of the
points you are making).  Be slightly animated, be comfortable, use a rich
voice, make eye contact, know your material, rehearse, and prepare.

There is a whole lot more, but this should get you started and should help
put you about 80% of the presenters out there.

If you do all this, your presentation should be well received.