There are several extensive tutorials available on the Internet that show you how to fix various Mac problems that many users encounter. Moreover, there are also many small tools that will help you out with just a few clicks of a mouse.
In this guide, I will introduce several such applications and explain the problems that they can fix.
Jettison 1.4.3 (Shareware, $4.95) by St. Clair Software
This application was designed to help users that commonly use external storage devices, like USB flash drives, external hard drives or SD cards, and forget to manually eject the device before unplugging it, which might cause a loss of transferred data. If you have done this, then, surely, you have encountered the Disk Not Ejected Properly notification.
Jettison allows you to automatically eject all the external disks the moment your Mac goes to sleep (you close the lid). This way, you can safely unplug your USB thumb drive or external HDD without risking any data loss.
But that's not all that this app can do. Jettison resides in your menu bar (as seen in the image below) and give you the possibility to quickly eject all the connected drives with one click, without having to switch to Finder and unmount each device.
Menu Bar Icon
Furthermore, if you decide to put your Mac to sleep, but you don't want to unplug your devices, then Jettison will automatically remount them. You can even tell this app which devices to disconnect by accessing the "Preferences" menu and selecting the desired options (as displayed in the image below).
Caffeine 1.1.1 (Freeware) by Lighthead Software
Battery life is one of the main concerns of any MacBook user, even though there are several improvements available. Most users tend to put their Mac to sleep when they don't actively use it. But this might not be the best idea, especially when downloading large files or waiting for an important message or call.
If you want to keep your MacBook awake for whatever reason, then the freeware Caffeine will help you out. This application resides in your menu bar and, when active (you just have to click on the coffee cup icon), it keeps your Mac awake for the desired period of time. You can set it for an indefinite period of time or for several minutes or hours by accessing the "Activate for" option, as seen in the following photo.
Menu bar icon and activation period
You can also configure the activation period from the "Preferences" menu or select to automatically launch and activate the app every time you will start your MacBook.
DwellClick 2.2.2 (Shareware $9.99) by Pilotmoon Software
For those of you who don't know it yet, Repetitive Strain Injury (RSI) is a muscle injury that occurs due to repetitive actions such as performing mouse clicks or typing. If you are suffering from RSI or you simply want to prevent this condition, then the application could come in handy.
DwellClick is a lightweight tool that was created to perform mouse clicks whenever you stop moving your mouse cursor. This way, you can easily diminish the amount of repetitive actions you make each day and even prevent injuries. After activating the app (a simple click on the cursor icon on the menu bar), it will start performing single clicks, but you can set it to perform double-clicks or even control clicks by holding down the "Fn" button and choosing the desired mode.
Menu Bar Icon
From the program's "Preferences" menu, you can easily change a delay between clicks, a placement and size of the pop-up panel that appears when pressing Fn (that I have mentioned before), specify what apps the program shouldn't click on and more.
QuickRes 4.2 (Commercial $4.99) by ThnkDev
Every Mac user knowns that constantly changing screen resolutions proves to be quite an annoying task as you will have to access the System preferences each time you modify it. If that is the case, then you might enjoy QuickRes. Also, if you own MacBook Pro with Retina Display and you want to properly display your screen, you might give this app a try.
QuickRes is a small utility that gives you the possibility to quirky alter your Mac's screen resolutions with just a click of a mouse. After installing it, this app will reside in your menu bar and will let you change between various resolutions, up to 3840 x 2400 (for MacBooks with Retina Display), even when using a 15-inch Mac. Furthermore, for legacy systems, QuickRes puts at your disposal resolutions with the HiDPI mode, which means that your screen will be displayed with a higher pixel density (as close to Retina Display as possible for standard monitors).
You can even create pre-defined resolutions and quickly change between them using hotkeys (keyboard shortcuts).
You can find QuickRes on the website.
f.lux (Freeware) by Michael and Lorna Herf
Most of us, Mac users, tend to spend a lot of time in front of computers, especially at night time, even though most of us know it is not a bright idea as it may interfere with our sleep. Since stopping the use of our Macs after nightfall doesn't seem to be a solution, this little app could help us out.
f.lux is a free tool created to make a color of your screen change according to the current time of the day (it will ask for permission to access your Mac location in order to determine the sunset and sunrise time). Basically, this app will adjust a color temperature (hue) of your screen by warming the colors during nighttime and cooling them down in order to match the sunlight during daytime.
f.lux menu bar icon
By accessing the "Preferences" menu, you will be able to modify a color temperature used for each time of the day (daytime, sunset and bedtime) and even specify the time you wake up so that the app can adjust the colors accordingly.
Furthermore, f.lux gives you the possibility to disable it for one hour (could be useful if you are a graphics editor or photographer that works during the night) or even make your screen look like a darkroom or enable the "movie mode".
You can download this app for free from the website.
As you can see, the apps presented in this guide will help you with various problems that many Mac users are struggling with. All these tools are very easy to use and I hope that they will come in handy for you to solve at least some of your problems.