Top tips for slide preparation

Which background?

For a presentation in a bright room, for example a lunchtime seminar, you need a light background. For a presentation in a dark room, for example a congress symposium, you need a dark background.

PowerPoint provides templates called 'Themes' under the 'Design' tab. Choose an uncluttered theme in the appropriate background shade. Your institution may require you to use a corporate slide template; hopefully there should a light and a dark version. If not, use the one provided because it is possible to change the shade later (but see 'Which colours?' below).

Which colours?

Try to use the 'Theme Colors', which appear at the top of the colour palette.

The colour palette pops up when you apply colour to an item. The theme colours appear at the top of the palette, with 'Standard Colors' in the middle, and 'Custom Colors' at the bottom. If you use theme colours you will be able to switch seamlessly from one theme to another in a single operation (for example from a dark theme to a light theme). However, if you use 'Standard Colors' or ‘Custom Colors’, these will not change when you change themes, necessitating a slide-by-slide, item-by-item edit of the old colours.
It is possible to change the theme colours to generate your own custom theme: follow 'Colors' under the Design tab. If it all goes horribly wrong you can always switch back to a predefined theme.

When is a slide too busy?

When it has more than 6 bullet points.

Remember: it takes the same length of time to present two nicely spaced slides as it does to present a single busy slide, and is less taxing on the audience. It is fine to use titles such as 'Demographics I' and 'Demographics II'.

Which font?

Use a sans serif font such as Arial, and use the same font throughout the presentation.

You want the audience to focus on the information, not the font. Serif fonts are difficult to read and comic fonts are a distraction. Changing fonts halfway through is also a distraction. You can provide emphasis using bold, italic, or a different colour.
One exception to the consistent-font rule is for showing DNA or peptide sequence, when you should use Courier (Courier is a non-proportional font, so each letter has the same width).

What size font?

Generally, no smaller than 18 pt in the body of the slide.

Try to be consistent with the sizes, for example 36 pt for all titles and 22 pt for all first-level bullets. Sub-bullets can use 20 or 18 pt. For references and footnotes you can use 14 pt, or if pushed, 12 pt bold, but no smaller.

Which punctuation?

Avoid full stops on slides.

On slides the layout often substitutes for punctuation. Do not use full stops in titles. Do not use colons before, and do not use full stops at the end of bulleted lists. It is OK to use full stops, colons, commas, hyphens, and en-dashes in blocks of text if necessary. Use double quotation marks only for reported speech ("I have a dream . . ."), otherwise use single quotation marks. For references, use the shortest form possible while retaining the author name, for example:
Dant C, et al. J Cancer Educ 2011;26:208–11