Step 1: The biggest problem with laptops are generally reliability. Figure out the reliable brands. Apple, Dell, Toshiba, and oddly Asus generally do well there, and Sony & HP are usually close to last. Start at those manufacturer sites.
Step 2: The major differentiation is in CPU type & Speed. Is it a quad-core i7? an i3? If you're doing video editing or realtime code debugging, you need a top level i7. For gaming, an i5 is fine, and for everyone else an i3 is AOK. Note: Everyone offers laptops in whatever screen size you want. So pick your screen size and ignore the rest. Also, ignore anything over 8 lbs. The weight is never worth it.
Step 3: GPU. If you need a gaming processor, configure the biggest the manufacturer offers. This can never be upgraded, there are no real options, and you can't get it later. So get it. If you don't need gaming, then Great! Nothing else uses the bloody thing, so don't bother.
Step 4: Battery length. It's usually worth splurging on the biggest battery you can find, so configure that into the build. Everyone has a "long" one that lasts about the same length. Look for manufacturers who have battery settings that keep the charge withing 20% min and 80% max... This will greatly extend the lifespan of that extra 100 bucks.
Step 5: Now figure out which setup is the closest to what you want, and go for it! Why haven't I mentioned RAM, Hard drive, software, or other optional extras? Because buying this from the manufacturer is flushing money down the toilet. Buy these after-market.