What are some guidelines regarding the use of type or font variants (e.g. italics)?

Some of the guidelines regarding the use of type or font variants are as follows:

1. Font legibility – this is extremely important because the use of fonts that are tough to read can confuse the readers. Some examples of fonts that are easily read are Arial, Times New Roman and Verdana;
2. Font consistency – although it is acceptable to use different fonts when highlighting a title of the page or a place, it should be used properly and in a consistent manner. If the use of fonts aren’t consistent, it would be hard to distinguish the main section and its sub-sections;
3. Font variation – there are several kinds of font variants such as italics, bold, oblique and underline. However, make sure to use these variants accordingly in terms of emphasizing important matters or words.