You don't need a non-admin account for your daily or "regular" tasks. Just work with an admin account. If you're worried about security, you're probably used to Windows security advices (back when it didn't have User Account Control).
Any administrative task will require you to type in an admin password to work anyway, so you can just work as an admin user. There's no benefit whatsoever in having a separate user for system administrative tasks if you are the person administrating the Mac. There's no security gained, and it'll only be a hassle to switch between user accounts.
On the other hand, if you share your machine, just run as a normal user, and you'll be prompted for admin credentials for any administrative task anyway.
Most common scenarios are:
- Changing system-owned files
- Installing applications or preference panes for all system users
- Installing applications that need to change system files
- Doing stuff with your boot partition
That being said, stuff like partitioning your boot drive can only be done with admin privileges (But why would you even change your system partitions so often?).
Also, most preference panes in System Preferences can be "locked" so that without a password, no regular user can change the settings (and even you need to enter an admin password then).