That question is no more easy to answer than what kind of car should I get . . .
There are many manufacturers with many models with different attributes and price ranges. I'll try to make this entry non-brand specific and able to be used in the future without mentioning models available the day I'm writing this.
In my opinion, the two most important factors when deciding which laptop to get are price and weight. Of the hundreds of options you have, this will narrow down your choices significantly. Most laptops weight between 3 and 8 pounds. Generally (but not always), the heavier a laptop is, the less expensive. Generally (but not always), the larger the screen is on a laptop, the heavier it is. Cost is always a factor. Generally, most laptops cost between $700 and $3000. For the most part, you get what you pay for. In addition to the cost of the laptop, you also need to think about software. Laptops almost never come with software (such as MS Word). You often need to buy that separately.
So the next step is to figure out where you are in the aforeomentioned categories. What is your weight limit and what is your price limit? Knowing that, it's time to start looking at what is available to you. My favorite places to look are PC Connection and Dell. PC Connection is an online retailer that sells virtually all brands of off the shelf laptops (made in a factory to certain predetermined specs). Dell is the leading seller of made to order laptops (you choose the specs of your laptop and they build it for you to your specs). PC Connection sells all brands of laptops (except Dell and a small minority) and Dell sells only Dell laptops. But between the two you are probably looking at 90% of the laptops available.
With PC Connection, you can look at laptops by weight and by price. For Dell, it takes a but more fine-tuning. For Dell, look at the screen sizes and use these approximations of weight.
17" screens - 7 pounds
15" screens - 6 pounds
14" screens - 5 pounds
13" screens - 4.5 pounds
12" screens - 3.5 pounds
Hopefully, this will lead you to what model and brand you want. Now, you need to think about software, operating system, memory, and warranty. For software, most people would order a version of Office: Home and Student for home or academic use, Professional (for office use), or try one of the free options like OpenOffice. A quick google or Amazon search will give you appropriate pricing. If Windows XP is still available as you read this, you will want Home for home users or Professional if you'll be using it in an office environment. If you are choosing Vista, you'll choose between Vista Home Premium for home users or Vista Business or Ultimate for an office environment. You do not want Vista Basic. Lastly, you'll need memory. You want 1 GB or more of memory for XP and 2 GB or more of memory for Vista.
You can always go to a Best Buy to look at laptops - which is also an option, and it's what a lot of people do. What I listed above is how I shop for laptops and how I shop for my client's laptops. If you have additional questions, please fee free to email me.