[Q] How to update CyanogenMod? topic

I know this is a very basic question; however, since I messed-up my phone the last time I tried to update it, I thought I had better ask.

I have an AT&T SGS 3 running CyanogenMod 10.2.0-RC1-d2att. The following are the "Available Updates":
cm-10.2.0
cm-10.2.1
cm-11-20140104-SNAPSHOT
cm-11-20140210-SNAPSHOT

Do I need to start with the oldest update and install them all? Or, can I just install the latest update? Also, (this is where I screwed-up before) at what point do I need to install an updated gapps file?

Thanks