The graphologist needs a handwritten document on a black A4, not ruled sheet.
The writer should use his normal style (printed, cursive, …) and his preferred writing instrument in his preferred color. Some more paper put under the writing sheet makes it easier for the graphologist to appreciate the pressure.

The text of the manuscript is irrelevant, but should be spontaneus: copying from another source might change some features of handwriting.

It is preferable to also analyse

• notes on scrap paper;
• a few documents from earlier on (5, 10, 15 years ago, for instance).

Graphology cannot deduce from handwriting either sex or age or level of education or profession. This is data that is required for the analysis, and must be told to the graphologist.

It is often useful to analyse (graphologically) also some drawing tests. The following ones are among my favourites.

The landscape test

Also called the four elements test. It requires an A4 sheet of paper. The instructions are:
Draw a landscape containing a house, the sun, some water and a snake.

The star-wave test

It requires an A5 sheet of paper on which a frame has been drawn, more or less half inch from the border. The instructions are:
Draw the starry sky over the waves of the sea.

The trees test (Stora)

The instructions are interactive and cannot be written here.