When much of your working day is spend looking at a computer screen, it is important that it be at the right height. This means that your head should be in a comfortable position and that your eyes are at the level of the screen. A simple and affordable way to ensure this is to use a riser on which you can simple place your screen. Another option would be an adjustable mounting arm, but that is a more expensive solution.
I like how this model also provides a shelf and a drawer:
Wood monitor riser pictured: Victor Technology 11755 Monitor Riser, 13 in.x13 in.x6-1/2 in., Midnight Black
Pictured above: 1-ROYAL CRAFT WOOD Luxury Monitor Stand Riser, Bamboo Office Desk Storage Organizer. 2-Designs2Go Small TV / Monitor Riser, Cherry by Convenience Concepts. 3-Samdi Universal Desktop Computer Monitor Heighen Wooden Stand Dock Holder Display Bracket for iMac PC Notebook Laptop (Walnut Color). 4-Prosumer’s Choice Natural Bamboo iMac Monitor Stand Riser | Desktop Organizer. 5-Vencer® “Charlie” Decorative Wooden Monitor Riser and Desk Organizer (oak)