From http://www.myfirstmac.com/index.php/mac/articles/5_things
1. Run Software Update There is no telling how long your new Mac was sitting on the shelf before your received it, so you should install the software updates that have been released since your Mac was manufactured. It is very simple, but it will take a while, so you can start it while you continue to use your new Mac. Using Software Update depends on your new Mac already having an Internet connection, so be sure to establish that first. To run Software update, open System Preferences (the light switch plate with gray Apple logo) that is in the Dock, or select it from the Apple menu in the top left. When that opens, click Software Update in the System row. On the next screen, click Check Now. After some time checking, a new panel will pop up listing software updates that apply to your Mac. Go ahead and click Install Items and click through the remaining buttons and passwords. Expect it to take some time to download and install the updates. It is likely that you will need to restart your Mac to use the updates, so don't start a big project on your Mac that you will have to cut out of.
2. Move and resize your Dock
By default, Apple puts the Dock at the bottom of your screen, but it can be located on the left, right or bottom. To make the most of your screen space, move the Dock to the right side of your screen where it won't limit the size of your Application windows. To do this, go to System Preferences again and select Dock from the Personal row. If you don't see all the preference choices, click the Show All button at the top of the window. In this Preference Pane, I suggest you select the Position on Right button and then adjust the Dock Size slider to reduce the width of the Dock until it doesn't cover the icons next to it. I also recommend that you un-check Magnification. This puts a stop to the effect that enlarges the Dock icons when you move your mouse over them. While this effect looks cool, it actually makes it harder to click the icon you want.
3. Add "Right-Clicking" to Your Mouse or Trackpad
Apple has long been criticized for making Macs with only one button mice and trackpads, but did you know you can still use a second button to "right-click"? For your new laptop this secondary click is done by tapping two fingers at once. You can enable this by going to System Preferences > Keyboard and Mouse > Trackpad and checking the box next to "Tap trackpad with two fingers for secondary click." While you are there, check the box for "Use two fingers to scroll" and "Allow horizontal scrolling." For your new iMac or Mac Pro, you go to System Preferences > Keyboard and Mouse > Mouse, and use the drop down menu pointing to the right side of the mouse to select "Seconday Button." If your are left handed, you can reverse the left and right buttons if you choose. Don't forget to take some time to explore all the options on this preference pane. A third and possibly better choice that some people still don't know about is that you can go buy your favorite USB mouse made by any other manufacturer and use it with any Mac, including the MacBook and MacBook Pro. Some come with their own software to install that controls all the options available.
4. Become a Full Citizen on the Internet
Safari will get you to most sites on the Internet, but because Windows computers dominate web usage, you will find some hiccups. The first thing is download the Flip4Mac Windows Media Player plug-in. Install this to view Windows Media files. You should also download the Real Player plug-in for when the only option is to view Real video. A few sites also don't recognize Safari, so download and use the FireFox web browser when you run into a problem.
5. Calibrate your Laptop Battery
Apple advises you to calibrate your new MacBook or MacBook Pro battery in the first week of use and every couple months after that. You can find directions on calibrating here on Apple's Web site. Additionally, Coconut-Flavour makes a great freeware application and widget that keeps track of all your battery stats including maximum capacity and the age of your Mac. Download it here on their web site.
Next Steps If you followed the tips above, you are now set up to use your new Mac a little more efficiently. I suggest that while your are reading this, you bookmark the MyFirstMac site so you can return to find help and learn more about your new Mac. After you are sailing along on the Internet, be sure to check out Apple's Mac 101 web site where you can learn much more about how to operate and get the most out of your new Mac. If you aren't connected to the Internet, you can still find the Mac Help program in the Help Menu of the Finder. In the Help Viewer there is a section called Discovering Your Mac where you can learn the basics of Mac OS X and explore the rest of your Mac.
DIG DEEPER
Helpful Sections of the Apple Web Site
Mac 101
Switch 101
Windows vs. Mac Navigation
Quick Assist Help Page
Mac Application How-to's
Apple's Main Support Site
Calibrate Your Battery
Dramatically Increase Productivity on OS X
DOWNLOADS
Flip4Mac
Windows Media plug-in
FireFox Coconut Battery