This is obviously a very open question as there are so many things you can do to speed up your computer. Much of which depend on time and budget.
However, while a fast processor and ample memory is key to a speedy machine, often one of the factors that get forgotten is just how quickly that processor or memory can access your data.
Opening up a picture of Uncle Fred with his snorkel on his holiday in 1969 is hardly something we'd be concerned at when it comes to the speed of the hard drive. However, when you drum your fingers on the desk after pressing the "ON" button, waiting for the operating system to fire up, or while you wait for your office suite to start, or your graphics software, it starts becoming a necessity.
In a recent machine upgrade at work, I was pleasantly surprised at the difference in speed in which my new PC got to the log in screen. In the past, I would switch the computer on, go make a cup of coffee and return to it waiting for my password. However, on the new machine, I am prompted for my password in a little over 30 seconds. Why?
Instead of the typical Hard Drive installed as drive "C", it has a SSD (Solid State Drive) installed. This is a drive that takes similar technology from the USB stick, memory banks that can remember the information even without power. The advantages are that the data can be retrieved in a flash, without waiting for the hard drive platter to start spinning, or the arm to whizz to the location where the first sector of data is stored.
While it can be argued that a standard hard drive is faster when it delivers a large chunk of data, strung together on the drive, fragmentation of the drive often means that this data is scattered around the drive thus slowing it down.
Fragmentation does not affect SSD, as the technology requires no moving parts at all, the access is almost instant. This means that booting up windows, firing up office, and general opening of applications and writing away of data is lightning fast by comparison.
Downsides? Well, typically cost is the main set back. For £49.99 you can either get a 128gb SSD or a 1024gb (1TB) Hard Drive.
My answer was to keep a regular hard drive in my computer with my unique data on it. The O/s and all associated programs are on the SSD. On my home computer, a slower machine than my work, I can still get booted up in under1 minute. I'm pretty impressed with that.
So, how do you make your computer run faster? Get SSD when you can next afford it, and you'll see a speed difference almost instantaneously.