Fixing a slow Mac

My main computer is a late 2009 13" MacBook with 2 GB of ram and  2.26 GHz Intel Core 2 Duo processor with OS X 10.7.3
I've used it for about two years and, in general, it's been flawless.
However, lately I've noticed it seems much more sluggish and lethargic than previously.
Even general browsing was slow, even though I use a 100 Mbps network, with much time "sending message" or "waiting for...." as if there was a DNS problem.

Time to fix this so I delved into google.
As expected, there are tonnes of stuff on this topic, in particular, many YouTube videos.
I found these three (first, second, third) to be particularly useful.

So, here's a list of what I did. The benefit I got was immense although, because I carried out many of the potential improvements together, I'm unable to make any definitive comments on which were the most efficacious.

1. Clean up your Desktop.
Besides your Macintosh HD, try to have, at most, just one more folder on the Desktop with all the stuff you frequently access. Everything else, keep in your home folder.
This makes a big difference.

2. Free up as much space as possible on your HD.
I have a 250 GB drive which had about 45 GB free. I put in a big effort to bring the free space to 105 GB.
Dick Inventory X is a wonderful free utility that very much helps to toss out the tonnes of useless stuff you probably have on your disk.

3. Take out the Dashboard, if you don't use it -- and I really didn't.

4. Reduce the number of spaces on your machine.
I had originally set up a total of four spaces and, honestly, I rarely if ever used more than just one.
How to do this is explained in this thread.
Interestingly, when I went to delete my extra spaces, I found my original four had grown to ten and I've no idea how this happened. In any event, I took nine of them out.

5. Repair permissions using Disk Utility.
Actually, this is something I do about once a month.
In fact, Onyx is another free utility that is very useful for permission repair and other general soft maintenance.

6. I also did a few of the tips in this video including System Preferences >> General >> Reduce all Number of Recent Items to None.


Now my Mac runs like new.
The secret is basically to avoid accumulating unnecessary stuff on your machine. Include only what you really need and will use rather than leaving stuff there for a rainy day.

Edit (27/05/2012):
I have now increased my RAM from 2 GB to 4 GB and, not surprisingly, this has also made a huge difference to the responsiveness of my Mac. See this post for details. Very worth while considering this as it's easy to do and is not expensive providing, of course, that your machine has spare memory capacity.