I'm going to look at as many beamshots posted by other people as I can find and take notes of what information they give about aperture settings, exposure times and ASA settings (or whatever they are called on digital cameras. And I think it's probably a good idea to keep detailed records of every shot and every change you make to exposure, aperture etc.
A further suggestion from Luke's point about EXIF data:
If you use the Firefox Browser, you can add an extension called "FxIF" which will allow you to right-click on web page images and retrieve the data. Keep in mind that this only works if the image file has not been stripped of it's EXIF data. An example would be where there are "composite" beamshots (side-by-sides) edited together into single images.
As an example, you can see this beamshot in one of selfbuilt's fine reviews. Although he has added the basic exposure info, the EXIF data is still retained in his file. If you right-click the image in Firefox, you'll see the following context menu:
Click the "Properties" item (highlighted above) and it will open a small image properties window. With the FxIF add-in, this info is expanded to include any embeded EXIF data, exactly what you are looking for:
As you can see, it includes not only the exposure information for the image, but details on when it was shot, whether a flash was used, his camera make and model, etc. etc. You can see that selfbuilt was using manual exposure control to make his images, as one would expect from this type of comparison work. The expanded properties information not only includes the EXIF info, but a handy "copy" button to copy the EXIF info into the clipboard if you wanted to compile this type of beamshot info by pasting it into another location.
EXIF data is extremely helpful in understanding the
technical "recipe" for a photographer's work. To be honest, it's been so long since I used Internet Explorer, I can't speak to any capability there, but for sure this kind of function can be added to Firefox and I find it super helpful.