Simplest in my opinion ...
Get a second harddrive dedicated to backing up your photos. Use CarbonCopyClone to clone that drive -- 1 step backup. Make the second drive 2x the size of what you use for photos, since you seen to actively use your photo library and will have many new entries addedd to the CarbonCopyClone backup.
True about TM's time-based restore. But the way I have CCC set up it has "time based folders" as well.
It is the OP's choice ultimately based on experience using clone and TM tools.
Just was pointing out that "backing up data" can be done with the same tool as "making a bootable startup-disk clone".
Don't know about the Best... But this works for me and has for a number of years...
One EXT Drive running Time Machine
Another EXT Drive for Cloning (SuperDuper)
A Third EXT Drive used for Manual BackUp
And Once a Month... or Before any Major Updates or Upgrades... A Fourth Cloned EXT Drive...
All Drives Formatted Mac OS Extended (journaled)
Most Simple Back Up
Drag the iPhoto Library from your Pictures Folder to another Disk. This will make a copy on that disk.
Slightly more complex:
Use an app that will do incremental back ups. This is a very good way to work. The first time you run the back up the app will make a complete copy of the Library. Thereafter it will update the back up with the changes you have made. That makes subsequent back ups much faster. Many of these apps also have scheduling capabilities: So set it up and it will do the back up automatically. Examples of such apps: Chronosync or DejaVu . But are many others. Search on MacUpdate
My own routine:
My Library lives on my iMac. It’s Backed up to two external hard disks every day. These disks are permanently attached to the iMac. These back ups run automatically. One is done by Time Machine, one is a bootable back up done by SuperDuper
It’s also backed up to a portable hard disk when ever new photos are added. This hard disk lives in my car. For security, this disk is password protected.
I have a second off-site back up at a relative’s house across town. That’s updated every 3 or 4 months.
My Photos are backed up online. There are many options: Flickr, Picasa, SmugMug etc. However, check the terms of your account carefully. While most sites have free uploading, you will often find that these uploads are limited in terms of the file size or the bandwidth you can use per month. For access that allows you to upload full size pics with no restrictions you may need to pay.
Every couple of months I test the back ups to make sure they are working correctly. It’s very easy to mis-configure a back up application, and the only way to protect against that is to do a trial restore.