Adding that Professional touch
An initial message - "It will start soon .." Open a blank slide, use the text tool and insert your message and format it appropriately. Create another slide with a similar message and change the font or colour slightly. In order to make the message appear to blink, choose view > slide sorter right click the first slide, choose slide transition. Select Automatically after and enter 1. Repeat with the second slide, choose View > Slide show , select use slide timings and loop continuosly until ESC.
Scrolling text box - Add a text box and add your text pressing Enter after each line. Select the text box and hold down Alt down, move the text box off the slide. Right click custom animation click effects tab, expand the list and select "Locate crawl from bottom". Check the list box labelled introduce text, select "All at once"