This site presents a thematic philatelic exhibit, and for those who are not familiar with them I compiled these notes to provide basic information.
A thematic exhibit tells a coherent story, from beginning to end, following a well-defined plan. This is a requirement in thematic exhibiting, and the exhibit plan and its development throughout the exhibit are as important as the philatelic material itself. Roughly speaking, the philatelic aspect and the thematic aspect receive the same number of points.
The plan of the exhibit should be shown at the beginning of the exhibit, usually following the title/introduction page. The latter includes an introduction to the theme and usually also an item. Since this item is not evaluated, it can be one that is not "exhibitable" (see below), even not philatelic (like an old picture postcard) - this is the only place in the exhibit that this is allowed.
Exhibiting in competitive classes must follow official rules and guidelines. In Israel we use the Special Regulations for the Evaluation of Thematic Exhibits of the FIP (International Federation of Philately). A very important aspect of the regulations is determining which items can be included in the exhibit. The general rule is that the item - or its element that is referred to - must be postal in nature and official (not made privately). Within the allowed material there are criteria to determine quality and preferences. It should be noted that in various countries different rules are applied, notably the USA where they follow APS (American Philatelic Society) rules. These rules, for example, allow the use of privately produced elements such as cachets (on first day covers, patriotic cover and special event covers) or advertisement covers and "corner cards". FIP rules do not allow them. You can find the FIP thematic regulations here (in PDF form).
As implied in the last paragraph, the exhibit does not include only stamps but all sorts of philatelic items, like postmarks of all types, stationeries (items with imprinted stamps), stamp booklets, watermarks. In fact, points are awarded for diversity of material and for finding unusual items that are related to the theme. The exhibitor is expected to point out and describe important philatelic aspects of the item, thus showing his philatelic knowledge (a thematic exhibit is still and foremost a philatelic exhibit!).
The text in the exhibit is only complimentary to the material and should be kept to a minimum. A thematic exhibit is not a story or thesis illustrated with stamps!
There is a rule that says that mint and used stamps cannot be included on one page. Practically, it means that an exhibit is entirely made of either mint or used stamps, but not both. Most exhibitors choose mint as it is easier to collect, and so did I. This applies only to stamps, not to stationeries and covers. However, since postally used items are considered better than mint ones, I used used stationery items where I can and I try to replace the mint ones with used ones.
Throughout the exhibit you will see covers with postmarks that are only partially shown - they can be recognized by the fact that not all sides have the black mount margin. This is called "windowing" and it is used to save space when the relevant element is a postmark and the rest of the cover is not postally important or interesting.