Back in the days I often got confused by using the words then/than. I never knew when to use which one, but it is actually very simple:
Than: Than is the word you want to use when doing comparisons. "Mike is taller than Peter."
Then: Then is used when talking about time. "I went to the store, then back home.
I think this is the easiest explanation I can come up with. I just kept thinking to only use "than" when I compare something, and with the other stuff that is left, "then".