Run Software Update. Be sure you have the latest software updates on your computer to ensure compatibility.
Try running Disk Utility’s “First Aid” function to solve some software issues. This can be run directly from your computer, or the DVD that shipped with your system.
Try reinstalling the Operating System (Mac OS X or iOS). Make sure that you have a proper backup of all of your data. When reinstalling your OS, make sure that you do an “Archive & Install” so that your data is left intact.
Reset your computers Parameter RAM. This can be done by holding down the Command-Option-P-R key at start-up. Keep them held down until you hear the computer restart 4 or 5 times.
Reset your iOS device by holding down the Home button and Power button at the time until the device powers off.
Keep at least 10% of your hard disk drive capacity free in order for the operating system to have adequate room to save and swap cache files.
Do not eat or drink near your computer. If an accident happens, any resulting damage would not be covered under warranty. Crumbs and such from food can get into your computer under the keyboard or through the vents.
Do not use your machine in a dirty or dusty environment. Enough dust can clog up fans causing overheating.
Do not smoke around your computer, the dust, nicotine, and particulate matter is electrically conductive and if enough builds up inside your computer it can cause an electrical short.
Run Time Machine, or back-up your data is some other way onto an external hard disk drive. Hard disk drive failures can occur without warning taking your valuable information or memories with them.
Shut down your computer on a regular basis to clear out system cache files, these can fill up your hard disk if left for long enough. Shutting down or restating your Mac also allows your Mac to run critical Unix maintenance programmes.
Keep third party utilities and software to a minimum. Running a lean, clean machine is the key to having a happy machine.