Here's what I usually do:
Close services that are running in the background that I'm sure I will never use (If you don't have a printer for example, why run that service?). Search for black viper on google you will get a good insight.
Use cleaning software as previously mentioned.
Clear the cache in your browsers and disable/delete any extensions you don't use.
Benchmark my DNS connections to find a faster one available (use Google, OpenDNS) instead of your ISP to speed up your internet.
Ensure your laptop is rested on a flat surface to avoid future problems from heating, when the fans get congested and tired. They don't work too well when they can't blow air back up towards the laptop.
Of course defrag your hard drive routinely.
If you're playing games use IoBit software to kill services that aren't required when you're using the game.
Keep drivers up to date from official sources of the hardware.
Download a one-scan anti-virus program from the internet and try different ones in the process. Then make sure you have a decent one.
Install a few extensions in your browser to prevent spam, and ads.
Use msconfig.exe as suggested to disable as many programs that delay your startup process.
You can use a flash-drive as extra virtual RAM, Google it, but I don't know how much overall benefit this has.
Un-install as many programs as you can from the control panel to reduce chances of spyware and other unwanted memory loss.
And also scan for spyware and delete it, perhaps with something less commercial like Spybot S&D.
You can preload commonly use applications into memory, how much this applies to Windows I don't remember since I've been using Linux for the past 3 years, and 7 years before that. Only switching to Windows when I require it directly rather than emulating or using Virtual machines.
For speeding up physical use of the machine, make sure your files are organized and your system is available for your most essential needs. Every bit helps to make it seem faster.
I can't think of many more tips, though I like to wipe free(empty) disk space on occasion, not that it helps at speed increases but there are tools to optimize your hard drive, atleast on linux there is.
You can upgrade components on your PC also which has probably been mentioned before here also.
