Note:
I'm not asking how. I've found nice tutorials on how to do this and will try it myself and I'll dig some more or ask questions about it after my first attempt.

Background:
I installed Ubuntu 12.04 LTS on my machine to dual boot with Windows 8. It's a ThinkPad machine so the disk is pre-partitioned for recovery and other stuff. I decided to do assign the mount points to the different partitions myself.

Stupidly, a friend of mine suggested to use one partition to mount / and /boot (swap is on a different partition of course!!).

So after doing some reading, it's clearly safer to have the two mount points on two separate partitions. I've decided to separate them and put /booton a different partition.

The thing is, I don't think I have unallocated space nor a free partition on my disk right now.

Finally:
So my question is: How safe is it to shrink the root partition to have some unallocated space on my disk, and use that space as a dedicated partition for /boot?

Thanks in advance.