1) First of all, you don't need to download any expensive software like "System Mechanic", "Avg Tuneup" etc to optimize your windows as they most of the time create more trouble rather than doing what they should do. So, try avoiding this software and look for the free alternatives.
2) Use the "Windows Disk Cleaner". It is a simple and effective tool to clean the system and it does a fair job in doing what its name implies. The engineers of the Microsoft Windows are clever enough to make their "Windows Disk Cleaner" effective for their users. There are a variety of options to choose for cleaning the PC as required.
3) Use the "Windows Disk De-fragmenter". It looks very simple but, believe me, it will replace all your other de-fragmenter software. It also has an option for scheduling the time for de-fragmenting.
4) If you prefer a system cleaning software then "CCleaner" can be a good option for you. It is such a wonderful cleaning software and also includes a registry cleaner. Just use the free version and it will be sufficient for your whole system. The great feature of the "CCleaner" is that it has the option to let you find out about your startup programs in detail. You can turn off useless extensions of browsers, or disable scheduled tasks which take the precious memory of the system.
5) You can also use the "Defraggler" for de-fragging the system. It's another great software from the same company of CCleaner "Piriform". The best thing about this software is that it can make your system's fragment almost zero. You can also confirm this by de-fragging from this software and then checking from the "Windows Disk Defragmenter". Just click on the "Analyze" for checking. Aside from de-fragging effectively, it can also defrag locked system files. For using this, open the Defraggler and click on the settings. From there select the option "Boot Time Defrag" and there you can select the time when to perform.
Note: These tips are very basic, but they are effective. I personally follow these tips and my system is running smoothly. Also, these expensive cleaning software creates more problems. You may find this kind of software have a very good rating on reviewing websites like the "Top Ten Reviews" etc but have you see free software on their website. So, what this implies is that these kinds of reviewing websites charge a huge amount of money from the pricey software making companies and in turn rank them on top.