Where is the carpet going? You may be buying carpet for a certain room of the house. Many different textures and colours of carpets can emit different feeling. If you want to get a carpet that will make your room look bigger, try to get a light coloured carpet. This is a generalisation, but it is usually a good rule of thumb for people who want to make their rooms seem bigger. If the carpet is light and a similar shade to the shade on your walls, then your room will look even bigger.
When buying carpet also think about the environment that your carpet will be in. I would not suggest for you to get light coloured carpet for your front room, if you have children that bring in a lot of mud. Although, many different types of carpet removal products do work, it is best to think about getting a carpet that will not look as bad when things are spilt or dropped on there.
Also if you have a dog or pet which you are training to be home friendly, it may be a good idea to get darker carpet. These are things that you must take into consideration whilst buying your carpet.
I would also recommend that you think about pricing, more luxurious carpets are often more expensive. The carpets that cost more are often carpets that have thicker texture. Is this essential for you, or is it low down on your list of priorities. Either way this is something which you must consider if money is an issue. Younger child are usually better with thicker carpet, because it doesn't not graze their skin, and is less likely to give a carpet burn, if they fall. However if you buy carpet that is reasonably priced, then you should not have this problem whatsoever.
Taking these few things into consideration will help you to get a carpet which will get great for you. Take these into consideration and you will have no problem.