Address it to the correct Department or Editor. Most Editors prefer a typed rather than handwritten manuscript. It should be double spaced and printed on one side of reasonable quality A4 paper. Pages should be numbered consecutively. As regards fastenings - loose leaves are acceptable provided they are enclosed in a sturdy folder or envelope.
Editors generally dislike pins, paper clips or more than one staple.
Enclose a covering letter with your manuscript. The letter should be polite and to the point and addressed to the Editor by name. Make sure you spell their name correctly. Before you submit the manuscript, proofread it. Check the spelling and punctuation.