I have read a lot of different books by a lot of different authors, some renowned, some unknown, and I have come to the conclusion that the SF writer needs the reader’s trust. In these days of relatively cheap fiction, losing the reader’s trust is the end of the relationship. The reader isn’t likely to look at that author’s work again.
When the trust is there, readers are likely to cut the writer some slack. That unexciting training lecture in the second chapter will be glossed over in the hope of something more interesting to come (soon). The reader will patiently wait for an explanation why the aliens were doing handstands while they planned their invasion of Earth. The reader will accept the nonsensical on the assumption that it will all make sense at some stage.
Of course, if your work is well known, if there are a lot of voices enthusing about it, the reader’s trust comes a little easier. But suppose, you aren’t. Suppose you’re self-published like me. Trust can be a fragile thing. Your main focus must be on securing it.
I know that very deliberately, it is mine.