Blogging Challenge T(ense)

Are your characters tense? Or maybe you're tense? Perhaps you're tense because you can't figure out what tense you're writing in?

So here are some questions for you.

Say your WIP is written in first person, past tense. Your main character talks about people and their characteristics. Some of them are dead, so it's not misleading to talk about them in the past tense.

But what about the characters who aren't dead--and still have those characteristics? Do you continue to write in past tense, implying that either the characters are dead or they no longer have those character traits? Or is it ever appropriate to jump tenses and move into the present tense?

How do you handle knarly tense problems?