Let your PC boot up entirely before opening any applications.

Refresh the desktop after closing any application. This will remove any fresh files from the RAM.

Do not fix very big file size images as your wallpaper. Do not go on a wallpaper at all if your computer is low on RAM

Do not clutter your Desktop with a many shortcuts. Every shortcut on the desktop uses up to 500 bytes RAM

vacate the recycle bin always. The files are not actually deleted from your hard drive until you empty the recycle bin.

Delete the temporary internet files always.. Defragment your hard drive once every 2 months. This will free up a many space on your hard drive and rearrange the files so that your applications run faster.

invariably make two partitions in your hard drive. Install all large Softwares in the second partition. Windows uses all the available empty space in C drive as virtual memory when your Computer RAM is full. Keep the C Drive as empty as possible.