1. Wallpapers: They slow your whole system down, so if you're willing to compromise, have a basic plain one instead!
2. Drivers: Update your hardware drivers as frequently as possible. New drivers tend to increase system speed especially in the case of graphics cards, their drivers are updated by the manufacturer very frequently!
3. Minimizing: If you want to use several programs at the same time then minimize those you are not using. This helps reduce the overload on RAM.
4. Boot Faster: The 'starting Windows 98/XP' message on startup can delay your booting for a couple of seconds. To get rid of this message go to c:\ and find the file Msdos.sys. Remove the Read-Only option. Next, open it in Notepad or any other text editor. Finally, go to the text 'Options' within the file and make the following changes: Add BootDelay=0. To make your booting even faster, set add Logo=0 to remove the Windows logo at startup.
5. Restart only Windows: When restarting your PC, hold down Shift to only restart Windows rather than the whole system which will only take a fraction of the time.