Make copies of your slides available. It is a matter of preference whether you do this at the beginning of your presentation or at the end. If your listeners have copies at the beginning, they can take notes simply by annotating the slides, instead of having to note down all the information on the slides. On the other hand, you might feel that, if they can see in advance the slides you are going to use, you lose the element of control or surprise. It might depend on the content of the presentation: if you are going to show detailed tables or graphs with lots of figures, your audience will probably find it easier to have a copy on their lap. It might depend on the circumstances of the presentation: if there is a large auddience, people at the back may not be able to see the screen clearly and would really appreciate having copies of the slides.