One. What kind of paper?

A simple lined sheet is all right. Four guidelines together are better than baseline alone. (You can download them from this site.) And a few sheets, one on top another, are better than a single one, especially on a hard surface.  

A blank page is not a good choice.

Two. Paper position (wrong and right)

Wrong: On the left (red sweater) the paper is too far to the left. As a result, the girl cannot see what she’s writing at the beginning of each line. This is a common error.

Right: On the right (green sweater) with the paper slightly to the right, the line of vision is clear.

Thr. What kind of pen?

Try a few. Use whatever feels right. 

Soft pencils make dark lines that reveal what needs improvement. Hard pencils make light letters look neat and tidy at first glance . They hide bad habits.

Advice about giving fat markers to small children is far less convincing in practice than it is in theory.

Four. Pen hold

Any grip you like is fine, provided it doesn’t give you writing cramp. Different approaches have been taught and used over the centuries. Most worked.

One bad habit you must stop before it takes hold: the pen barrel must never lie parallel to the thumb. It is not suited to the demanding control of pen movements.

Five. Low-tech assistive device

A triangular pen grip on your pen or pencil can help developing a trouble-free hold. Writing need never be painful. ry it if you ever get writing cramp. There’s no need to suffer.