The standard way to lay out an orchestral score (reading from top to bottom) is as follows:
Woodwind
Brass
Percussion
Others
Strings
There are often variations within these groupings, with individual instruments occupying different positions depending on composer or historical practice.
It is generally best to use separate staves for each instrument if possible. Brackets or braces to the left of the system identify the groups, and the full name of each instrument should appear on the first page, with abbreviated versions on every subsequent page.
Be sure to give rehearsal letters as well as bar numbers. This will speed things up in rehearsal.
Scores are usually presented with all transposing instruments correctly transposed. Concert-pitch scores do exist, but most conductors are familiar with transposed scores.
When preparing instrumental parts, be sure to give cues and allow time for page turns. In the full score, eliminate staves that have no content for significant periods of time.
Click the links above for pictures of typical layouts, section by section, with comments. Single woodwinds and a selection of percussion have been used for illustration.
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