I repeat the golden rule: “Keep it simple, and then even simpler”.

Later on I will explain that whatever you do, when you start preparing your sheets, start with the master slide(s).

General structure

File size

This has nothing to do with minimizing the number of sheets. It all depends on how large (in bytes) your figures and graphs are. Make small presentation-quality compressed bitmap files (like jpg) out of large bitmaps (like tiff files) or out of large vectorized figures (like ps and eps).

The size minimization will help to load your slides fast (slow loading is irritating for your public) and in fast saving during preparation. Small files will also help in prolonging the life of the battery charge on your laptop.

Reusability

In the field of software engineering reusability is a paradigm. Structured computer languages as C++ are designed with reusability as major design goal. The ‘re-user’ can be yourself at a later point in time, or one of your group members. To make individual sheets reusable they must be loosely coupled. That is to say they must be usable without reference to other sheets.

If you buy a cupboard or bed from a furniture shop, your new purchase looks beautiful from the outside or front side. If you look, however, at the rear side, or under your new bed, you will discover a lot of not-painted, not-finished woodwork. The reason is economy: why spend effort (money) on something that no one ever sees.

The same applies to digital presentation sheets. You can import oversized pictures, group, cut and paste and do ugly things with nontransparent boxes. As long as it happens outside the margins or below other drawings, no viewer will ever notice the chaos.

Yet this minimal, carpenter approach limits seriously the reusability. For another user your slide will look like one big mess. I have seen examples where people put the whole sheet in a title box. Even PowerPoint stupidly suggests doing so in its template for new slides. It works, but it is awful, amongst other things because the Normal View is meshed up. Be disciplined and try to do away with the carpenter approach. If your colleague group members still use this messy practice, correct them.