Upgraded the CPU in many laptops. It varies from quite simple to major pain but here are the usual tips I give.
Look up the laptops chipset, that should tell you the range of CPUs it can handle.
As mentioned in the article look up on Google for "CPU upgrade for Laptop XYZ", chances are 20 other people have tried or failed and they will tell you what works and what doesn't.
Upgrade the BIOS if you can. That will update the CPU list potentially.
Look up disassembly on YouTube first if possible. If it looks really tricky and the laptop is quite old...then don't bother.
I don't tend to go crazy with the upgrade. Top end vintage cpus go for crazy money but usually the one below it (the 3.0GHz rather than the 3.16GHz will often be a lot cheaper. Plus I try to keep in the same thermal/power rating. So say we have a 1.6GHz C2D installed as standard then I'll hunt down a 2.0-2.1GHz C2D for a nice boost. Also I'll look for one with more cache.
I've also found that swapping a 1066 bus CPU for a 1333 bus CPU can often allow your 1333 ram to run at that speed. That gives a nice boost too.
Haven't had too many issues. Maybe a little more cooling fan action but as the laptop is maybe 5+ years old anyway if it only lasts another couple of years then thats fine.
The last laptop I did was to swap out a dual core Athlon II mobile chip for a quad core 2.0Ghz Phenom mobile chip. Made a big difference. The chips usually cost around £20 on Ebay.