With the release of Mac OS X expected on July 25th, there are a few things you need to take care of before upgrading.
First of all you must make sure that all the applications you use on a daily basis actually work on 10.8, normally this would be a pain, as you’d have to check all the developers websites for information on updates, but there is a website you can check which should help you in this instance
http://roaringapps.com/apps:table
If the applications that you use will all work on 10.8 then you can move on to the next step
Does my hardware meet the minimum requirements?
you can find out from this page on Apples Website
http://www.apple.com/osx/specs/
If you meet those requirements then the next step would be ensuring that your system is actually ready for the upgrade
First, ensure your Hard Drive is in good health, you can do this with Disk Utility, (located in /Applications/Utilities)
Open that and click on your Hard Drive (not the volume name) and you will see information from the Drive, the bit we are interested in is S.M.A.R.T. Status – make sure this is Verified, if not then you will probably need to invest in a new hard disk.
If it does say Verified then you will need to verify the directory structure of your currently installed OS, you can do this by following the instructions here
http://itsallmacademic.com/video-tutorials/maintenance/verify-disk/
If you get a red message stating that your disk needs repairing then view the following video for how to resolve this.
http://itsallmacademic.com/video-tutorials/maintenance/repair-disk/
Once that is complete and you have a green message stating that your hard drive is OK then you will need to run a Permissions Repair, which you can see how to do at the following page
http://itsallmacademic.com/video-tutorials/maintenance/repair-permissions/
OK, so now that is all done, your system should be fit and healthy, all ready for the new OS, but wait, do you have a backup of your data? if the answer is no then you should take a look at Carbon Copy Cloners knowledgebase article on backing up to a disk image
http://help.bombich.com/kb/dmg-and-remote/backing-up-to-a-disk-image
If you have any 3rd Party Encryption software running then I would disable that before upgrading, I do the same with Filevault, but thats just me being over cautious, although if you are running 10.6 I would recommend disabling it as the filevault program is quite different from 10.6’s and you don’t want to run into any issues with inaccessible data after upgrading.
Now, after all that, you are ready, it’s up to Apple to release the software now, I’ve been using the Developer Preview versions and the recent GM version, and I like it a lot, the integration with iCloud and all of the info that I have on my iPhone/iPad is great, and the ability to mirror my laptops display onto my TV through Airplay (an Apple TV is also required) is great, no more messy cables to be plugged in trailing across the floor.
Check back for more tips on Mountain Lion in the not too distant future.