Are there any "to do" items I should be thinking about when I first fire up the system? For example, with a Windows system I would normally (i) install some open source antivirus software,
You don't need any 3rd party antivirus app to keep a Mac malware-free, as long as you practice safe computing, as described in the following link. Read the
What security steps should I take? section of the
Mac Virus/Malware FAQ for tips on practicing safe computing.
There isn't any on Mac OS X.
(iii) install some basic system diagnostic tools,
Mac OS X has those built in. You don't need to "manage" or "maintain" OS X, as it takes care of itself. Use
iStat Pro (free) or
iStat Menus ($16) to get accurate readings of your battery, temps, fan speeds and much more.
For example, with a Windows system I would normally (i) defragment discs, (ii) repair HD, (iii) physically clean the system etc.
You don't need "cleaner" or "maintenance" apps to keep your Mac running well, and some of these apps can do more harm than good. Some can even degrade, rather than improve system performance.
Some remove files/folders or unused languages or architectures, which does nothing more than free up some drive space, with the risk of deleting something important in the process. These apps will not make your Mac run faster or more efficiently, since having stuff stored on a drive does not impact performance, unless you're running out of drive space.
Some of these apps delete caches, which can hurt performance, rather than help it, since more system resources are used and performance suffers while each cache is being rebuilt. Caches exist to improve performance, so deleting them isn't advisable in most cases.
Many of the tasks performed by these apps should only be done selectively to troubleshoot specific problems, not en masse as routine maintenance.
Mac OS X does a good job of taking care of itself, without the need for 3rd party software. Among other things, it has its own maintenance scripts that run silently in the background on a daily, weekly and monthly basis, without user intervention.
With very few exceptions, you don't need to defrag on Mac OS X, except possibly when partitioning a drive.
About disk optimization with Mac OS X
You probably won't need to optimize at all if you use Mac OS X.
Browsing around I found this:
Sound advice?
There is no advantage to running a non-admin account in OS X. The default account is an admin account. Unless you are sharing a Mac with another user, there is no need to create another user account.
This may be useful:
