Clues to using the perfective

[paul_a_j]

Aspect oh my giddy aunt!
Anyone like to comment on my reasoning below?
I have a series of sentences and I need to choose imperfective or perfective.
Example
Usually I read (imp) a newspaper but today I read (perf) a book.
I know adverbs like usually (обычно) every day (каждый день) are a good clues to use the imperfective as they indicate habitual actions. If they are following an imperfective verb phrase before but (но) the verb is often perfective as it is not a usual action. (okay so far?).
If I have two verb phrases separated by "then" as in "I read the book then watched television" is the verb "read" liable to be in the perfective as it is a complete act?
All help gratefully accepted
Cheers Paul

[TeneReef]

"I read the book then watched television"
I would use
a) imperfective aspect for both verbs here, if you read a part of the book.
b) perfective + imperfective if you read the whole book