Not only is Being Published distinctly weird, now you've got to write another book. Maybe it's under contract, or maybe it's just that everyone's expecting you to write another. So why is it being so difficult? I assume that, even before you or your agent got an offer for One, you were hammering away at Two and you're halfway through it ... aren't you? Really? And you haven't told your agent?
Come on, I'll make us a pot of tea, you open the chocolate biscuits, and we'll have a think about this.
1) You don’t have as long. You may have taken a decade to write One; now your contract says you’ve got a year for Two. Or you have no contract, but you know that the longer the gap before Two comes out, the harder it will be for your publisher to drum the world’s interest back up. Now, if never before, you need to allocate writing time before everything else, ring-fence and defend it ferociously (even, if necessary, from what your publisher would like you to do), tackle any procrastination, and dig deep into Rachel Aaron’s fantastic advice for writing a lot in very little time.
2) Being Published is very distracting. To get people to buy One you must look outwards, and communicate with the world of readers and book-buyers; to write you must reverse your engines and look inwards, through your imagination, to communicate with the developing world and words of Two. It’s worth working out some strategies for when you get home or shut down Zoom, to help you recover from the sugar-rush then sugar-low: sleep, hot baths, baking, baby-cuddling, mountain-biking. Once unwound, you need strategies to help you climb properly back into your head: free-writing, walking, the right music or café noises, yoga, reviewing last week’s work.
3) Good things happening can be as distracting as bad ones. Having bad reviews, or no reviews, or getting bad news about sales, is horrible, and can really dent your writerly confidence; some of these remedies for writer's block should help. But good reviews or prize nominations can also really throw you: they "ought" to encourage you, but when you look down again at Two, you can't see how it could possibly achieve the same things – and yet complaining about your good fortune sounds privileged and spoilt-bratty. The fundamental problem is that these things too are essentially external to Two, nothing to do with its reality - so the same remedies should help.
4) Someone else owns part of your writing now. If it’s under contract, with the advance for Two, your publisher has, as it were, bought shares in it. And your agent kind-of does, by having committed at least in principle to representing you for the long term. But even if Two isn’t under contract, it’s hard not to feel that more people have a stake in your writing. The only way to deal with this is to recognise that publishing is gambling, not manufacturing. You are not an engineer but a racehorse owner, and your agent, your publisher and your family are the punters backing your horse. You'll do all you can, and take all the help you can get, to keep your horse fit and healthy, well-trained and well-ridden. But in the end whether it wins, where, and by how much, is not in anyone’s complete control, and certainly not in yours.
5) Two must be the same, but different. True, the first port of selling-call for Two will be those who liked One, which means Two needs to be the same kind of book - whether in delivering the same genre satisfactions, or grabbing literary readers with the same kind of tastes. And it's true that if it was word-for-word the same, those readers would feel cheated. But while that's true of the overall book, I'd suggest that the more you try to micro-manage producing Two by a page-by-page ticking all the little boxes that One seems to tick, the more you risk losing touch with the logic and heart of Two's story.
6) If One was a success, you feel you have to beat that; if it was a failure, you feel you have to beat that. But Kipling’s If is right about triumph and disaster being imposters, and the industry labels "success" and "failure" are too: they impersonate useful labels such as "works" and "doesn't work", and can lead your ordinary, creative common sense and self-knowledge very, very badly astray. That's not to say that your business head should ignore realism about the business of your writing – but one of your business head's principle jobs is to protect your writing head. As Tim Gallway's concept of the Inner Game knows, what wins matches is forgetting what happened last month, or last point: all that matters now is to watch the ball coming towards you, and decide what to do, now, with this ball and this opponent. As my agent said to me at exactly this stage: "Just write it. We’ll worry about everything else later."