A Design Toolkit Consists....

Color
Type Styling
Weight and Scale
Structure
Grouping
Graphic Elements
Imagery
Sound and Motion

All of these things help to guide a user and all of it is intentionally thought out. Color helps with isolating elements, directing the eye to a given location, and hierarchy.

Type styling is another method of providing hierarchy you could do this by highlighting, bold font  of playing with different typefaces to clarify varied types of content in a book that is very text heavy. Even things like boldfaced content headers help readers quickly find what they need without having to sort through all the fine detail.

Weight and Scale its all about patterns and as humans we are subconsciously looking for them after reading a word long enough we recognize a pattern and then when we see it we no longer sound it out or actually read it we already know what it is though a recognition process. Thats why sometimes changing these patterns like using all caps can confuse the user and slow down the experience because the design is unrecognizable. Changes in scale and weight can show the importance of certain things compared to others.

Structure deals with the grid. Using a grid  and capitalizing on white space can help the user navigate through complex information, it keeps things organized, and can also create a since of importance/hierarchy.

Grouping is another way of organizing information so that it helps users quickly locate what they are seeking, it can help show importance, create hierarchy, and maximize readability and coherence.

Graphic elements are things like lines, rules, and bullets which are things that designers use to attract the eye (good for showing direction). It can also show attention to detail, give it a since of time, and create visual interest.

Imagery  is a powerful component, it is said that putting images together with words is one of the most powerful ways in having the user retain the information that they have read. You go out of the way to read text if you are interested in a subject, or you are required to do so for a school subject, but only imagery can stop you and make you read something you never intentionally wanted to read just because a photo intrigued you to read it.

Sound and Motion is the last thing that is combined with these tools to convey a clear design message it is another wat to help the user retain information, it is a way of learning something twice, and really allowing the information to sink in, you are hearing it and seeing it at the same time.