You can use tools like contrast and spacing to help differentiate elements.
Other techniques are useful for visually associating similar elements.
These techniques are often used in combination – when you group a collection of links, for example, you also differentiate the group from the elements around it.
Techniques for creating associations
Associating elements implies a relationship of similarity, e.g. A, B, C are a group of equivalent ‘peer’ elements.
Groups can be created using any combination of the following mechanisms: