1) Use font size that will be large enough to be seen clearly from the back of a room when projected (at least 18 point font, I use 28 or 32 point for most everything on presentations). Do not try to put too much on a single slide or overhead.

2) Present enough background and introductory material for an audience unfamiliar with your particular field of study to understand the larger significance of your work.

3) Speak slowly and clearly. Don't worry about presenting ALL your results.

4) Avoid tables - put your info into a graph, diagram, or sentence. Also, simplify graphs - the audience needs to be able to get the general idea quickly. When showing a graph, the very FIRST thing you should do is TELL the audience what the axes are. This helps them understand your graph quickly.

5) Make sure that your background color, texture, or picture does not interfere with the readability of your text. It doesn't matter how pretty your slide is if the audience can't read it!

6) Define terms and abbreviations!!!! This is an interdisciplinary audience. Do not expect everyone to know what you are talking about. For example, do you know what all these mean?: AFM, TEM, XPS, ICP-AES, XRD, XAFS, tRNA, GC-MS, NMR, AMD, K-spar, SMOW, PDB, BIR, BTEX compounds, MOPS, PCR, LPS, TCA-cycle, smectite, a, magnetosome, siderophore, saprolite...

7) Practice, practice, practice so that you know you will be within the time limit and you can relax knowing how you will express your thoughts. Practice in front of others - at your research group meeting, for example. They can tell you what parts are confusing.