If you're swapping out your hard drive for a new one, the best thing to do is clone the old one first. Cloning a drive creates an exact sector-to-sector backup copy of your drive. It's a perfect image of the original, including all OS files. So when you swap out your old drive for the new one, you don't have to tweak or reset anything.
For cloning a hard drive on a Mac, I highly recommend a free utility called Carbon Copy Cloner (CCC). Here's how to use CCC to clone a hard drive on your Mac.
First, download and install Carbon Copy Cloner (CCC).
After downloading it, installation is a piece of cake. Just double click on the Carbon Copy Cloner mounted icon.
Select and drag the CCC icon into your Application folder.
Now, from the Applications folder, launch CCC. Just double-click on its icon.
The first time you launch CCC, it will prompt you to read the Quick Start Guide. Do it later. Click on No Thanks.
Now down to business. Do you know what drive you'll be using to create the clone? I recommend an external drive. Regardless, if you've just bought a new internal or external drive, or are using one previously connected to a Windows machine, you're going to have to reformat it first.
Microsoft Windows FAT32 or NTFS file system comes on most new drives and it isn't Mac-compatible. If you have a new drive from the Apple Store or preformatted for Mac, you can skip this step.
So before going on with the CCC process, access the Disc Utility in OS X. This will reformat the drive with Apple's HFS+ file system for Intel Macs. I'm using an external drive, so I just plug the external drive into the Mac and power on the drive.
On recognizing the new drive, OS X will prompt you to back up your current drive's data with Time Machine. Don't do it. Click Don't Use.
Then click Go on the Finder toolbar and select Utilities.
Scroll down a bit. Double-click on Disk Utility.
In the Disk Utility, highlight the external hard drive in the left panel. Under Volume Scheme, select 1 Partition. Under Volume Information, give the drive a memorable name. Also, date it so you know when it was created.