You know the saying, "Clean house, happy family", right? The same philosophy applies to your computer. If you take good care of your computer and treat it well, it will treat you well and you will enjoy using it more. Here are a few tips to keeping your Mac running optimally.
Tip #1: Only install necessary apps
As fun and tempting as it may be to install lots and lots of apps (especially when there are so many free apps available these days), be selective and picky. Only install apps that you really need, and never install apps that seem questionable. If the source of the app isn't reputable, err on the side of caution and resist the urge to install (at least until you do more research). Also, if you no longer use an app, get rid of it. This will help to keep your hard drive and Applications folder clean and minimal.
Tip #2: Periodically run Repair Disk Permissions
Over time, your hard drive can suffer from subtle file permission amnesia. This can result in apps not running properly (unexpectedly quitting) and even sluggishness. To fix this, I recommend repairing the disk permissions once in a while (about every month or so should suffice). To do this, open Disk Utility (/Applications/Utilities), select your boot partition on the left (typically named "Macintosh HD"), then click "Repair Disk Permissions". You may want to run through the utility a couple times to catch everything. This is less critical with SSDs, but I run it anyway. It certainly can't hurt.
Tip #3: Limit the number of users
Avoid letting too many people use your computer, if you can help it. A favorite saying of mine is "Don't touch my tech". If I'm the only one that uses my laptop, I know everything about it, inside and out. If I allow others to use it (especially not in sight), I have now lost that assurance. In our family, I have my laptop, my wife has her laptop and the kids have a kids' computer. No one touches dad's laptop but dad, no one touches mom's laptop but mom, and the kids use their computer. I know this may seem a bit harsh, but it virtually guarantees that mom and dad's laptops run smoothly at all times. The kids' computer? Well, you know how that goes. I essentially write it off. :-) If you do need to let multiple users use a single computer, use profiles and set permissions accordingly. Limit the number of users that have full Administrator access to the system.
Tip #4: Keep it clean (physically)
When I was a young teenager, I learned how to drive on a 1972 red Volkswagen Bug. It was difficult to drive, but I loved that car. I was proud of it, and I showed it respect. I washed and waxed it nearly every week, and it shined. As a result, it handled as well as a 1972 Volkswagen Bug could. I do the same with my MacBook Pro with Retina. Obviously not with hot, soapy water, but with the proper cleaning solutions and a micro-fiber cloth. As a result, my 6-month-old laptop looks (and runs) like brand new. I have seen my fair share of computers with all sorts of food, smudges and crayon marks all over it (not to mention potato chip crumbs inside the keyboard). It's a clear sign that it's not taken care of.
Tip #5: Keep it organized
Keeping your files organized is important to helping you feel comfortable with your computer. That extends to your Desktop as well. Take a little extra time here and there to keep things tidy and organized. I have one folder on my Desktop called "WIP" (Work in Progress), as you can see below.
This folder contains files that I'm currently working on, and need to be in the forefront. When I'm done with them, I will put them in their appropriate location elsewhere. It's also a good idea to purge files once in a while. I guarantee that there are files on your system that you can permanently delete, and you won't skip a beat.