[dworth]

Writing sequels:

1) Consistency within the world. This is much harder to do with sci-fi fantasy where you're making everything up and it's harder to remember what you called something the first time. Make sure you have notes to refer back to.

2) A character's 'voice' is unlikely to change unless a considerable amount of time has passed between the books, or something very drastic has happened to them in between. POV change is acceptable of course. The focus of the book can change. Indeed many authors write books set within the same fictional universe but use completely different characters each time, so that you can appreciate some of them as standalone books.

3) If things are unresolved from Book One, don't overburden the second book with too many new development, it will start to collapse under it's own weight.

4) Make sure it's clear both in the title and the cover blurb that this is Book Two or 'The Second Book by'. You could even go back and rename the first one as Book One of the whatever series is called to make it even clearer. You'd be surprised how many full commercial releases fail to do this, resulting in the need to get hold of a physical copy of the one of the author's books and look at the publication order in the 'Also by:' bit.