Hiya!

What location is it?

In my experience with tours, the better the quality of your exhibit the better the tour. Average quality can actually hurt your tour. If your exhibits are Pristine Quality you can show less exhibits.  Ensure all your exhibits are well decorated and have maximum buzz and aren’t too long and are in a nice order. 

For higher tour ratings, you should try to achieve the following:

1.  Select only exhibits that have the exact same subcategory and main category, e.g., Fossils (Prehistory).

2.  Select exhibits that are higher quality (e.g., pristine or epic), consider replacing lower quality exhibits with higher quality versions as you find them on expeditions.

3.  Maximize the buzz and decoration of each of those exhibits.

4.  Keep a tour short, try to keep all of the exhibits you select for a tour close to each other.

5.  Use a tour guide with "Tour Guidelines" qualifications and/or the "Eloquent" trait.