Well, first, the biggest thing about keeping a transformation coherent is knowing where you will end up. Not, like, every specific thing, but you should have a rough idea about:
- How the subject will interact with their environment,
- How being that end state might feel, physically,
- How their mental state will be after all is said and done, and so on and so forth.
That way, you can build towards those things as you go, which makes the whole affair feel more fluid and like one single process instead of a bunch of growth scenes smashed together.
Also, knowing that stuff helps to build sensuality because with the character feeling far more fleshed out, the scene really lives–if that makes sense. Like, as much as the end state is the payoff for a lot of folks, for me, the emotions and sensations along the way are what get my motor running.
See, with a general idea of where you are going, it is easier to create meaningful signposts along the way. Knowing what a character wants or how they feel about something means you can play up an element of growth here or there to push the character’s (and the reader’s) pleasure buttons. Especially when you can focus on things which are either:
- exactly what the character wanted from the experience
- are like discovering a new dish they enjoy eating, which can be satisfying in a completely different way.
Those moments of peak sensuality are what drives someone’s response during the journey.
Another point, which cannot be understated, is to use descriptions that evoke sensation and make fewer fruit/sport ball comparisons. Instead of writing “she grew tits to rival the size of soccer balls” go with something more like “she groaned as her boobs continued to expand in her arms. It felt like she was trying to hug two milk jugs and, with every breath, her full-armed grip on her bust grew wider.”
Further, as much as you can, know how things feel. Talk to people about their orgasms and how penetration feels. Talk to people who like being spanked, people who like being tied up, etc. If you can, experience the sensations yourself. If you like giant(ess) stuff, put yourself in a small space, feel the way the walls press against you and how stifling that can be. Step on some stuffed animals, go to the grocer and get some empty boxes to make buildings with. Then, knock them over. Lay on a sand dune or a hillock and feel how your body curves around ‘the mountain” If you are not someone with boobs, but enjoy BE. Do yourself and every woman a favor. Buy a pair of heavy-weight pantyhose and, like, twenty pounds of playground sand. Fill up both feet, and hang them around your neck. That will give you a very rough idea of how much even just a 36E weighs. Spoiler: a 36E is about 1kcc which is about two pounds and that, doubled, is probably about how much your laptop weighs–if not more. By the way, a gallon of milk weighs between 8.4 and 8.6 pounds and that works out to 3kcc which is roughly a 38M/36N/34O for a 60″ bust! So when you have someone expand to Chelsea Charms size, keep in mind that is the kind of weight they are dealing with. For your own edification, to get the weight in pounds of a cc volume, multiply by 0.0022 to get what one breast theoretically weighs.
As for “good” erotica in general, it is ALL ABOUT THE MOJO. I am not talking about characters getting along either. The most satisfying scenes for me are two (or more) characters surpassing something that separated them to forge a new level of connection. Yes, not every sex scene needs to punctuate emotional growth, but I still need chemistry and you know what they say about opposite charges…