StyleChoosing a lamp is really a matter of what style or mood you want to express. However, some choices are certainly better than others. Always identify the style of the room then determine your style that goes together with the room. Choosing a lamp that is the same style as the rest of the room can make a strong statement about that particular style. If you prefer mixing styles (e.g. modern style with traditional settings), it is important to make sure there are other items in the room that can unify the styles together.
Lighting NeedsWhat is the lamp's purpose? To provide ambient? For reading purposes? Identify the function of the lamp so it can provide the correct lighting needs.
WattageIf there are other light sources in the room, a 60 watt bulb may provide enough light for a room. However, if you plan to use one or two lamps to light up a room, consider 100 to 150 watt bulb (or a 3 way bulb in some cases). A reading lamp should offer 150 or more watts. In general, rooms should have a light source every 10 feet or so.
LampshadesA semi-transparent lampshade gives a room a softer look.
A lampshade that has little transparency provides more concentrated light pattern.
A lampshade that has a wider brim at the bottom will spread the light out toward the bottom. This is good for a reading lamp.
For general purpose lighting, choose one with some degree of transparency, such as glass that is light in colour.
SizeTypically, short or narrow lamps are more appropriate on smaller tables and bulkier and taller lamps are better suited on larger tables or surfaces. A lamp located on a buffet table and other narrow surface should typically be more narrow or shorter. On a petite nesting table or a narrow console, a tall and narrow candlestick lamp may be the best choice.
BulkIf the table lamp needs to assist in visually anchoring an area - then a lamp with more bulk or visual weight such as a pottery jar lamp may be the most appropriate. Table lamps should not compete with the overall design of the room but compliment it.
ColourThe colour or material of the lamp can also affect a table lamp's dominance in a room. The lamp will have a strong design element when there is greater contrast in the color of the lamp to the color of the walls or room setting.
The table lamp should never block a view or get in the way of conversations.
HeightThe hardware should not be visible to someone sitting in a chair. The bottom of the shade should be about even with a person's cheekbone when sitting on a chair and the light's beam should fall on the page when reading.
And finally, make sure that there is some weight or other stabilizing feature to the base of the lamp so that is cannot be easily toppled over. The table lamp should also look good whether it is turned on or off. Ultimately, it has to fit your liking as you will be the one looking at it all the time!