How To Write A New Time Travel Series

Poul Anderson's works include a time travel series based on the possibility of causality violation, "changing the past," and some single works based on the circular causality paradox. It would be difficult to write a series set in a single immutable timeline although that is what I would prefer.

Write some independent historical, contemporary and futuristic novels without any overt references to time travel, then show that some of the characters had been disguised time travellers. If a time traveller, for example, had worked in the bar at the Cavern Club knowing in advance that the Beatles were about to make their first appearance there, then that time traveller's experience would, for me, be a sufficient basis for an intriguing narrative. We do not need causality violations, attempts to change the past etc.

Of course that is just my personal opinion.