Just a thought that often, New riders want to know..how to go about getting a new bike.
So, what is the best advice? I think you need to have a budget, which then allows you to set parameters. If for example you only have $1000-$2,500, then I would say go for a good aluminium road bike (assuming it's road we are looking for) and say above $3000, then start to look at Carbon.
Thing is a good aluminium bike, will be as fast, or faster even than a cheap Carbon bike.
Firstly though, the bike must fit you well, that is be the right size for you. There are ways to find this out on the net, don't rely, or trust the bike shop to do this for you, as they don't always get it right, it depends on the guys at the bike shop, and how experienced they are, or if they just want a sale.
The more you pay...the less you get..ie lighter, bike. The more expensive the carbon frame for example, generally will be lighter, and yet stiffer too to transfer you pedalling power.
A good carbon frame, will soak up and dampen, road vibration. Aluminium frames are often stiff, and give quite a harsh ride, but as mentioned, can be light, and so competitive, when combined with that stiffness.
Entry level racing bikes, well probably shimano 105 componentry. After this, you can go up in Quality, ultegra, and then Dura Ace.
If your brand new to cycling, don't go for that $10,000 bike. As time goes by, your knowledge increases, and you may decide on another brand then the one you may have just bought, get a decent bike for you budget, get time in the saddle, and then, you have a better knowledge base, and experience to make a much better informed decision. Hey you might end up, not liking cycling that much, and well would that not be waste.
Anyway, other comments from other members about what would be a wise start or decision on buying a bike.