Your show will look more professional and your audience will appreciate being able to read your slides. Do not use a font with serifs like Times New Roman. That type of font has letters that are made up of skinny lines and they do not stand out well from the background. Those individual letters are made up with thicker lines and they look much better on the screen. Simplify your design time by using a built-in template.
Most programs have slide templates already made up with a dark background and light colored letters.
White and light backgrounds glare at the audience, which makes your text very difficult to read. PowerPoint automatically defaults to an on-screen show page size. 35mm slides are a wider rectangle. Then send your file to us for processing. Apply the K.I.S.S. rule.