Re: Not very helpful tips
The best tip that I would give a novice user is:
Consider un-installing every program that you can replace with a web app instead. Some people will find that they only need to optimize their computer to run Internet Explorer and perhaps Google Chrome. I mention Google Chrome because it lets you install chrome apps that cannot be accessed without the chrome web browser.
Advanced/Expert users are much more difficult to give advice that they have not already heard of. The only thing I could think of is to recommend fine-tunning the system to a specific purpose. For example, if the system is used as a home server, you could potentially reduce it to a command-line only system and manage it with remote consoles.
For a general purpose system, get ready to do some serious homework. Start logging performance data and evaluate the requirements of your must-have applications vs. the physical resources that you have. You will have two choices, either eliminate unecessary programs/processes or increase your hardware capacity by upgrading or replacing the system altogether. If you're a kid and don't have much money, then consider taking one of the thousands of online gigs available to work up some kind of budget.