Use a large sans-serif font (helvetica, or the LaTeX sf font).
Avoid changing to smaller font sizes as much as possible.
Do not cut and paste equations or figures from papers using a screen capture. The result is always sloppy and unreadable. Retype the equations instead. If this is too cumbersome, you are using the wrong software.
The paper you are presenting might contain a wealth of ideas. You need to pick and choose the ones that makes sense to present to an audience in the amount of time allotted. A generic outline of your presentation could be: motivation for the problem being addressed, background required to follow the talk (introduce the required notation here, keeping it to a minimum), overview of the ideas of the paper, details of (some of) the ideas of the paper, results and comparisons, if available and as appropriate, concluding with summary and potential extensions.
Time yourself. If you are given a 30-minute slot for your presentation, plan to finish it in 25 to 27 minutes so that there will be three to five minutes for questions. Nothing ruins a talk more than a speaker that runs out of time and cannot present the main ideas of the paper. Stealing some of the next conference speaker's time is not an option.
Rehearse you talk multiple times in front of a mirror, favorite pet, family member, friend, or colleague. This will allow you to time yourself (see the previous point) and to familiarize yourself with what you want to say and when you want to say it, so that you will deliver your talk naturally. Speakers that read their own foils as if it is the first time they see them are bound to make a horrible impression.
Arrive to the site of your presentation ten minutes before your start time, and make sure your laptop can correctly interface with the projector. At many conferences, each session has three or four 30-minute talks; in this case, you should arrive before the beginning of the entire session and introduce yourself to your session chair; often, the session chair will ask the speakers to download their presentations to a single laptop, to reduce the switching time between speakers; again, make sure your presentation works on the laptop-projector combination; of course, you should not leave the session before all the other speakers in the session have delivered their talk. It is a good idea to carry a USB key with your presentation on it, in case your laptop gets stolen, stepped on, rained on, etc.
During your presentation, make eye contact with the audience. Position your laptop so that its screen faces the audience, and remain oriented toward the audience as much as possible. Nobody wants to stare at the back of your head for long. Of course, you should never point to the laptop screen, but only to the projector screen, using a telescopic or laser pointer; most conferences provide the session chair with a pointer, but it is a good idea to purchase and carry your own, to be safe. I personally much prefer a telescopic non-laser one, as I find it much easier to use (for the speaker) and to follow (fvor the audience).
In large conference venues, you will have to wear or use a microphone, it is pointless to try to avoid this reality, so don't be shy. If the microphone is a clip-on style, be sure that your clothing (tie, jacket lapel, scarf) does not brush against the microphone head, as the resulting (amplified) noise is extremely distracting.