Q:

What tense should we use to talk about the habits of a dead person?

Is it correct to say: "Franklin used to wake up early to read and write"?
Franklin is dead and I'm talking about his daily habits. So, what tense should I use?

A:

What you have written is perfectly correct.
But to summarise, the tense used for describing the life of a deceased will depend on whether you are recording a specific event, something that took place over time, or something habitual.
Lets say I was writing a biography of the English footballer - Stanley Matthews. I might say the following.
Specific event in the simple past:
In 1953 Stanley Matthews was the hero of the Cup Final in which Blackpool beat Bolton 4-3.
Something that relates to a period of time - the imperfect:
Between 1932 and 1947 Matthews was playing regularly for Stoke City
For habitual matters - the modal would, or used to:
When he was a boy Matthews would/used to practise dribbling with a tennis ball, around obstacles in the back garden of his home.

