First consider your lifestyle and your dining table use.
Casual or formal? Will the table be used for other functions other than dining? The majority of dining tables come at a fairly standard height of 76cm. You need to keep this in mind if you want to try looking for an unusual table not intended for dining. Apart from the different shapes that tables come in, there are some wonderful retro choices, refectory and trestle options.
2. Next consider what size is best for you.
How often do you entertain and for how many people? This will give you an idea of what size to choose from. There are some good sites that give excellent details about dimensions and seating numbers like House Plans Helper.
Generally for an average dinner party of 6 people, you are looking at:
122cm diameter for a round table
122-152cm for a square table
79x152cm to 91x183cm for a rectangular table
Depending on the space you have, you have options of round, oval, square and rectangular. The most flexible choice is an extension table, either square or rectangular, that can be easily expanded in length to accommodate more guests when needed.
3. Choose a dining table material.
For casual dining you could go for an outdoor dining set in wicker with a tempered glass top. The glass top is very practical and easy to clean. Marble is another excellent table top surface. If you are thinking about buying a wood table, be prepared for some simple but necessary upkeep. You will need to wipe the surfaces down with an oil-based furniture polish every six months and using coasters and placemats will minimise staining and scratching.
So go classical wood or contemporary glass and metal and enjoy an entertaining lifestyle.