John Kane, A Type Primer , writes:

To determine your grid you need to understand the amount of text and images, the kinds of images and text, the levels of meaning and importance, the relationships between test and image the relationship between text/images and reader.

Columnar Layout

There are columnar arrangements of books (from Ellen Lupton’s Thinking With Type site):

Working from a hang line. From Ellen Lupton’s Thinking With Type site.

Modular Grids

More complex information, say an annual report (see below) or a book written in multiple languages requires a modular grid:

Building a grid. Grid Studies. Book and editorial designers move back and forth between page size and proportion, thumbnail sketches, typeface specimens, body text studies and grid studies.

Achieving Swiss Modern page layout. Above is from a lecture by Frost Design.

Modular Grid used now that additional information has been added. From Ellen Lupton’sThinking With Type site.

Approach #1:
Use your optimal Body Copy, Leading and Line Length to build the grid layout and page height.

Approach #2:
Select the Page Size and Proportion, then create a series of body copy studies within those proportions to develop the grid and layout.

A) Begin by basing your page height on the a multiple of your leading, with or without the margins (see below). B) Use evenly divided multiples of the leading to determine the horizontal grid (see below for printed page and web).

Above from Ellen Lupton’s Thinking With Type site

The ultimate resource in grid systems: templates (Indesign, web and photoshop grids), books and more: The Grid System.org. The Grid System is an ever-growing resource where graphic designers can learn about grid systems, the golden ratio and baseline grids. Created byAntonio Carusone.

C) Use your optimal line length for your columns and build a grid around it.

Anything from 45–75 characters is widely regarded as a satisfactory length of line for a single-column page set in a serifed text face in text size. The 66-character line (counting both letters and spaces) is widely regarded as ideal. For multiple column work, a better average is 40–50 characters. —Robert Bringhurst