Put commas before FANBOYS:

For – presents rationale ("They do not gamble or smoke, for they are ascetics.")

And – presents non-contrasting item(s) or idea(s) ("They gamble, and they smoke.")

Nor – presents a non-contrasting negative idea ("They do not gamble, nor do they smoke.")

But – presents a contrast or exception ("They gamble, but they don't smoke.")

Or – presents an alternative item or idea ("Every day they gamble, or they smoke.")

Yet – presents a contrast or exception ("They gamble, yet they don't smoke.")

So – presents a consequence ("He gambled well last night, so he smoked a cigar to celebrate.")